Display device

ABSTRACT

A display device in which an image with a wide color reproduction range and bright red can be displayed is provided. The display device is a display device such as, for example, a liquid crystal display device, a cathode ray tube, an organic electroluminescent display device, a plasma display panel, and a field emission display. The display device includes a display surface including a pixel having red, green, blue, and yellow sub-pixels, wherein the red sub-pixel preferably has the largest aperture area.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display device. More specifically,the present invention relates to a display device preferably used in aliquid crystal display device, and the like.

2. Description of the Related Art

Currently, various display devices have been used in variousapplications. A common display device provides color display using apixel including sub-pixels of three primary colors: red, green, andblue. In such a liquid crystal display device, chromaticity of colordisplayed in each sub-pixel is adjusted so that the color has a highchroma. As a result, a range of colors which can be displayed (colorreproduction range) can be extended. In this case, a transmittance oflight which passes through a color filter arranged in each sub-pixel isreduced. Accordingly, use efficiency of light is reduced, and therebywhite having an insufficient lightness is displayed.

For this problem, a multi-primary color display device which includes ayellow sub-pixel having a color filter with a high transmittance, inaddition to red, green, and blue sub-pixels, is proposed (for example,refer to Japanese Kokai Publication No. 2001-209047). Such a liquidcrystal display has a configuration shown in FIG. 36, in which pixels 11w each composed of four sub-pixels 5Rw, 5Gw, 5Bw, and 5Yw which displayred, green, blue, and yellow, respectively, and the pixels 11 wconstitute a display surface 500 w. In addition, the following colordisplay device is disclosed. A pixel includes sub-pixels of five colorsof red, green, blue, cyan, and yellow, and the sub-pixels are arrayed inthe first repeating pattern of red, green, blue, and yellow or in thesecond repeating pattern of red, green, cyan, and yellow. These liquidcrystal devices include a yellow sub-pixel having a color filter with ahigh transmittance, which suppresses a lightness of white from beingreduced. Further, the number of primary colors is increased. As aresult, the color reproduction range can be extended.

In a conventional four-primary-color display device, the number of theprimary colors used for display is just increased and sufficient displayqualities are not obtained. In a display device shown in Japanese KokaiPublication No. 2001-209047, according to a display device having adisplay surface constituted by pixels each including red, green, blue,and yellow sub-pixels that are the same in aperture area (an area of aregion used for display (active region or effective region)), an imagewith a wide color reproduction range can be displayed, but displayed redis dark. As a result, visibility is deteriorated.

U.S. Patent Application Publication No. 2005/0134785 also disclosed aconventional display device.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention have been made in view ofthe above-mentioned problems. Accordingly, preferred embodiments of thepresent invention provide a display device in which an image with a widecolor reproduction range and bright red can be displayed.

In a transmissive liquid crystal display device including a displaysurface defined by pixels each having red, green, blue, and yellowsub-pixels, there is a lightness of each color (displayed color), first.According to a conventional four-primary-color transmissive liquidcrystal display device including a display surface 500 w constituted bypixels 11 w each having a red sub-pixel 5Rw, a green sub-pixel 5Gw, ablue sub-pixel 5Bw, and a yellow sub-pixel 5Yw, which are the same inaperture area, as shown in FIG. 36, a lightness of each displayed coloris as shown in Table 1. As shown in FIG. 37, according to a conventionalthree-primary-color transmissive liquid crystal display device includinga display surface 500 x constituted by pixels 11 x each including a redsub-pixel 5Rx, a green sub-pixel 5Gx, and a blue sub-pixel 5Bx, whichare the same in aperture area, as shown in FIG. 37, a lightness of eachdisplayed color is as shown in Table 2.

TABLE 1 Color Red Green Blue Yellow Cyan Magenta White Light- 11.0 33.47.6 48.0~92.4 43.4 18.6 100 ness

TABLE 2 Color Red Green Blue Yellow Cyan Magenta White Light- 23.8 66.110.0 89.9 76.1 33.8 100 ness

Tables 1 and 2 show a lightness of each of six typical displayed colors:red; green; blue; yellow, cyan, and magenta. The lightness of eachdisplayed color corresponds to a Y value in CIE 1931 (standard)calorimetric system (XYZ calorimetric system) and it is represented by avalue relative to 100 of a lightness of white. In addition, a colorfilter is arranged in each sub-pixel of the transmissive liquid crystaldisplay device. In any transmissive liquid crystal display device, acolor filter having a spectral transmittance shown in FIG. 7 ispreferably used. These transmissive liquid crystal display devicesdisplay an image using a backlight (light source is a cold cathodefluorescent tube (CCFT, CCFL)). Spectral characteristics of this lightsource are properly adjusted such that chromaticity coordinates of whitepreferably satisfy x=0.313 and y=0.329, and that and the colortemperature is about 6500K. In Table 1, the lightness of yellow widelyvaries. This shows the following results. In the case where yellow isdisplayed using the yellow sub-pixel 5Yw and without lighting the redsub-pixel 5Rw and the green sub-pixel 5Gw, the lightness of yellow showsthe smallest value (48.0). In the case where the red sub-pixel 5Rw andthe green sub-pixel 5Gw as well as the yellow sub-pixel 5Yw are lightedto display yellow, the lightness of yellow shows the largest value(92.4). In the case where the red sub-pixel 5Rw, the green sub-pixel5Gw, and the yellow sub-pixel 5Yw are lighted at a proper ratio todisplay yellow, the lightness of yellow shows a medium value.

From the results shown in Tables 1 and 2, it can be seen that in theconventional four-primary-color transmissive liquid crystal displaydevice, the lightness of red, green, and blue are lower than those inthe conventional three-primary-color transmissive liquid crystal displaydevice. This is because an increase in a number of primary colors usedfor display increases the number of sub-pixels per pixel, and thereforean area of each sub-pixel is relatively decreased. That is, the numberof primary colors used for display is increased from three to four,which decreases the area of each sub-pixel to ¾. Further, a visibilityof green or blue is not deteriorated even if the lightness thereof isreduced, but red becomes darker by the reduction in lightness and thevisibility of red is easily deteriorated.

FIG. 38 shows spectral characteristics of a light source used fordisplay in a conventional four-primary-color transmissive liquid crystaldisplay device. FIG. 9 shows spectral characteristics of a light sourceused for display in a conventional three-primary-color transmissiveliquid crystal display device. According to the conventionalfour-primary-color transmissive liquid crystal display device, the pixelincludes a yellow sub-pixel, in addition to red, green, and bluesub-pixels. Therefore, white with a yellow tinge is displayed if a lightsource having normal spectral characteristics shown in FIG. 9 is used.Accordingly, in order to adjust a color tone of white, a light sourceshowing a high color temperature, which emits blue at a high intensity,as shown in FIG. 38, is used. For example, if a CCFT is used, blue lightis emitted at a higher intensity, and green and red are emitted at a lowintensity. In such a manner, the color temperature is increased. If awhite light-emitting diode (LED) is used, a blue component is emitted ata higher intensity and a yellow component is emitted at a lowerintensity, and thereby the color temperature is increased. Further, ifred, green, and blue LEDs are used, green and red components are emittedat a low intensity and a blue component is emitted at a high intensity,as in the CCFT. As a result, the color temperature is increased. Thus,according to the conventional four-primary-color transmissive liquidcrystal display device, the color temperature of the light source isincreased in order to adjust the color tone of white. If the colortemperature of the light source is increased, the yellow and redcomponents of the light source need to be emitted at a lower intensity.As a result, the intensity of the red component of the light source isdecreased.

As mentioned above, in the conventional four-primary-color transmissiveliquid crystal display device, the increase in number of the primarycolors used for display reduces particularly the lightness of red, andthereby the visibility is deteriorated. Further, if the light sourcehaving a high color temperature is used to adjust the color tone ofwhite, the lightness of red is further reduced and this reductionfurther deteriorates the visibility. However, unlike in a conventionalfour-primary-color transmissive liquid crystal display device, a brightred can be displayed if the red sub-pixel has the largest aperture areain the pixel including the red, green, blue, and yellow sub-pixels, andas a result, the visibility can be improved.

Further, such operation and effects can be also obtained theoretically,not only in a transmissive display device including a display surfaceincluding pixels each having red, green, blue, and yellow sub-pixels,but also in a transmissive liquid crystal display device including adisplay surface including pixels each having a magenta sub-pixel, inaddition to red, green, blue, and yellow sub-pixels. Furthermore, suchoperation and effects can be also obtained not only in transmissiveliquid crystal display devices but also liquid crystal display devicesin other display systems, such as reflective or transflective liquidcrystal display devices, and the following various display devices suchas, for example, cathode ray tube (CRT), organic electroluminescencedisplay device (OELD), plasma display panel (PDP), and field emissiondisplays (FEDs) such as, for example, a surface-conductionelectron-emitter display (SED). As a result, the above-mentionedproblems have been admirably solved, leading to completion of thepresent invention.

That is, preferred embodiments of the present invention provide adisplay device including a display surface, the display surfaceincluding a pixel having red, green, blue, and yellow sub-pixels,wherein the red sub-pixel has the largest aperture area (hereinafter,also referred to as “the first display device”).

The first to twelfth preferred embodiments of display devices arementioned below. The first to twelfth preferred embodiments of displaydevices according to the present invention are the same in that an imagewith a wide color reproduction range and bright red can be displayed. Inthis common point, the first to twelfth preferred embodiments of displaydevices according to the present invention are far superior to theconventional display devices.

According the first preferred embodiment of a display device of thepresent invention, a display surface is defined by pixels each includingred, green, blue, and yellow sub-pixels. In the present description, the“pixel” means the minimum element on the display surface, and the pixelsindependently provide a color or a brightness to display an image. The“sub-pixel” means a point with a single color defining the pixel. Thecombination of the sub-pixels defining the pixel may not be the sameamong the pixels. For example, if sub-pixels of red, green, yellow, andtwo blues having different color characteristics (referred to as “thefirst blue” and “the second blue”) are arranged, a pixel includingsub-pixels of red, green, the first blue, and yellow and a pixelincluding sub-pixels of red, green, the second blue, and yellow maydefine the display surface. The pixel is defined by sub-pixels of aplurality of colors and displays a desired color using light including acombination of a plurality of colors. In preferred embodiments of thepresent invention, the pixel includes a yellow sub-pixel in addition tored, green, and blue sub-pixels. That is, according to the first displaydevice according to preferred embodiments of the present invention, thenumber of primary colors used in displaying an image is larger than 3,and therefore it can display an image with a wider color reproductionrange, in comparison to a display device which displays an image usingthree primary colors. The pixel may include a magenta sub-pixel, inaddition to red, green, blue, and yellow sub-pixels, but it ispreferable that the pixel includes only red, green, blue, and yellowsub-pixels in view of a transmittance of color filters in displayingwhite. If the pixel includes the magenta sub-pixel, the use efficiencyof light of the color filter might not be enhanced because the magentasub-pixel has a color filter with a low transmittance. In addition, evenwithout the magenta sub-pixel, magenta with a high purity can bedisplayed by increasing the color purity of the red and blue sub-pixels.The pixel configuration (pixel pattern) is not especially limited. Astripe pattern, a diagonal pattern, a square pattern, and the like, maybe mentioned.

The above-mentioned red sub-pixel has the largest aperture area. Asmentioned above, if the red, green, blue, and yellow sub-pixels have thesame aperture area, the reduction in lightness of red might deterioratethe visibility of the display device. According to a preferredembodiment of the present invention, the red sub-pixel has the largestaperture area in all of the sub-pixels, and therefore the lightness ofred can be improved. As a result, the visibility of the display devicecan be improved. In the present description, the “aperture area” meansan area of a region used for display (active region or effectiveregion). Examples of a method which relatively increases an aperturearea of the sub-pixel include (1) a method in which a proportion of anaperture area relative to an area of a sub-pixel is uniform among all ofthe sub-pixels, and a sub-pixel an aperture area of which is relativelyincreased has the largest aperture area among all of the sub-pixel; and(2) a method in which an area of a sub-pixel and a proportion of anaperture area relative to the area of the sub-pixel is uniform among allof the sub-pixels, and the number of a sub-pixel an aperture area ofwhich is relatively increased is the largest. Method (1) is preferablein order not to complicate the structure. According to method (1), anincrease in number of switching elements such as, for example, a thinfilm transistor (TFT) arranged to drive each sub-pixel can be minimized,for example. The lightness of red is preferably about 12% or more andmore preferably about 15% or more relative to the lightness of white. Ifthe lightness of red is larger than the lightness of white by about 30%,red seems to be emitted when white is displayed, which results inunnatural display. As a result, the visibility might be deteriorated.Accordingly, the lightness of red preferably accounts for about 30% orless relative to the lightness of white, and more preferably it accountsfor about 25% or less.

If the respective sub-pixels are largely different in aperture area, therespective sub-pixels are largely different in pixel capacitance. Thatis, if the respective sub-pixels are largely different in aperture area,a charging rate, a drawing amount of a pixel potential by a gate signal,and a variation amount of a pixel potential by a source signal arelargely different among the sub-pixels. As a result, defects such asflicker, image sticking, and cross talk might be generated. Accordingly,it is preferable that an aperture area of the red sub-pixel is abouttwice or less as large as an aperture area of a sub-pixel whose aperturearea is the smallest. However, the above-mentioned defects might beeased by properly designing a size of the TFT, a storage capacitance,and the like, taking a difference in pixel capacitance intoconsideration. In this case, it is preferable that the aperture area ofthe red sub-pixel is about three times or less as large as an aperturearea of a sub-pixel whose aperture area is the smallest.

The configuration of the first display device according to preferredembodiments of the present invention is not especially limited. Thefirst preferred embodiment of a display device may or may not includeother components as long as it includes, as a component, theabove-mentioned display surface including the pixels each having thered, green, blue, and yellow sub-pixels. According to the first displaydevice according to preferred embodiments of the present invention, theaperture area size relationship among sub-pixels in the pixel is notespecially limited as long as the red sub-pixel has the largest aperturearea and each of the sub-pixels other than the red sub-pixel has anaperture area smaller than that of the red sub-pixel.

It is preferable that the first display device according to preferredembodiments of the present invention performs display using a lightsource device such as, for example, a backlight and/or a front light. Itis more preferable that the first display device according to preferredembodiments of the present invention is a transmissive liquid crystaldisplay device which performs display using a backlight, a reflectiveliquid crystal display device which performs display using a frontlight, or a transflective liquid crystal display device which performstransmissive display using a backlight and performs reflective displayusing external light and/or a front light. According to this, even ifthe red sub-pixel has the largest aperture area, adjustment of spectralcharacteristics of the light source used for display easily permitsoptimization of the chromaticity of white displayed by the first displaydevice. In the present description, the backlight is not especiallylimited, and it may be a direct or edge light type one. The light sourceis not especially limited. A white light-emitting diode (LED), anRGB-LED, a cold cathode fluorescent tube (CCFT), a hot cathodefluorescent tube (HCFT), an organic EL, and the like may be used.

In the present description, it is preferable that a filter whichselectively transmits light having a specific wavelength (hereinafter,also referred to as a “color filter”) is arranged in each sub-pixel. Inthis case, the color of the sub-pixel is determined based on spectralcharacteristics of the color filter. The material for the color filteris not especially limited. A resin which has been stained with a dye, aresin into which a pigment has been dispersed, a material prepared bysolidifying a fluid material (ink) into which a pigment has beendispersed may be mentioned. The method for forming the color filter isnot especially limited. Examples thereof include: a staining method, apigment dispersion method, an electrodeposition method, a print method,an ink jet method, and a color resist method (“transfer method”, “dryfilm laminating (DFL) method”, or “dry film resist method”).

In the present description, five colors of the sub-pixels are defined asfollows. The “red” is a color having a dominant wavelength of about 595nm or more and about 650 nm or less if chromaticity coordinates of awhite point satisfies that x=0.3333 and y=0.3333 in the xy chromaticitydiagram in the XYZ calorimetric system (CIE 1931 standard calorimetricsystem). The dominant wavelength is preferably about 600 nm or more andabout 640 nm or less. The color purity of “red” is preferably about 75%or more and about 97% or less in view of subjective evaluation results.Evaluation results of the color purity range where an observer canrecognize that natural red is displayed show that if the color purity ofred is less than about 75%, red which is light in color and not brightmight be displayed. On the other hand, if the color purity of red ismore than about 97%, glare red like an emission color might bedisplayed, which gives unnatural red display. Similarly, the “green” isa color having a dominant wavelength of about 490 nm or more and lessthan about 555 nm or less, and preferably about 510 nm or more and about550 nm or less. It is preferable that the “green” has a color purity ofabout 50% or more and about 80% or less from the same viewpoint. The“blue” is a color having a dominant wavelength of about 450 nm or moreand about 490 nm or less, and preferably about 450 nm or more and about475 nm or less. It is preferable that the “blue” has a color purity ofabout 50% or more and about 95% or less from the same viewpoint. The“yellow” is a color having a dominant wavelength of about 565 nm or moreand less than about 580 nm or less, and preferably about 570 nm or moreand about 580 nm or less. The color purity of “yellow” is preferablyabout 90% or more and about 97% or less from the same viewpoint. The“magenta” is a color having a complementary wavelength of about 495 nmor more and about 560 nm or less, and preferably a complementarywavelength of about 500 nm or more and about 555 nm or less. It ispreferable that the “magenta” has a color purity of about 60% or moreand about 80% or less from the same viewpoint. The dominant wavelengthand the complementary wavelength generally represent a hue, and thecolor purity generally represents a chroma. The following method may beused as a method of measuring the color purity. Chromaticity coordinatesof a color in each filter in the case that the light source which isactually used in the display device is used as a light source aremeasured with a spectroradiometer and the like. Then, the color purityis calculated based on chromaticity coordinates (0.3333, 0.3333) of awhite point, the chromaticity coordinates of color in each filter, andchromaticity coordinates of a point where a line connecting the whitepoint to the chromaticity point of the color in the filter intersectswith a spectrum locus.

The first display device according to a preferred embodiment of thepresent invention is mentioned below in more detail.

It is preferable that the green, blue, and yellow sub-pixels have thesmallest aperture area. That is, it is preferable that the green, blue,and yellow sub-pixels have the same and smallest aperture area.According to this preferred embodiment, the aperture areas of the green,blue, and yellow sub-pixels are equivalently small, and therefore thelightness of red can be improved.

It is preferable that the pixel includes a sub-pixel whose aperture areais smaller than an aperture area of the blue sub-pixel. Yellow, green,white, red, and blue are generally ranked in descending order oftransmittance, with regard to a transmittance level relationship amongthe respective color filters arranged in the red, green, blue, andyellow sub-pixels, and the color filters for displaying white (anaverage transmittance of the color filters). In some cases, the red andblue are counterchanged, and yellow, green, white, blue, and red areranked in descending order of transmittance. According to thisrelationship, the blue sub-pixel has the smallest aperture area and theaperture areas of the other sub-pixels can be increased. As a result,the transmittance of the color filters for displaying white can beincreased. However, in this case, the color temperature of the lightsource used for display needs to be increased in order to maximize thechromaticity of white. If the color temperature of the light source isincreased, the light-emitting efficiency of the light source isdecreased. As a result, the lightness of white displayed by the displaydevice is reduced with the decrease in the light-emitting efficiency ofthe light source. Accordingly, such a reduction in lightness of whitedisplayed by the display device can be minimized if the blue sub-pixeldoes not have the smallest aperture area.

It is preferable that the green sub-pixel has the smallest aperturearea. The transmittance level relationship among the color filters, thetransmittance of the color filters for displaying white is reduced ifthe green sub-pixel has the smallest aperture area. However, in thiscase, the color temperature of the light source needs to be decreased inorder to maximize the chromaticity of white. If the color temperature ofthe light source is decreased, the light-emitting efficiency of thelight source is increased. As a result, the lightness of white displayedby the display device can be increased along with an increase in thelight-emitting efficiency of the light source.

It is preferable that the yellow sub-pixel has the smallest aperturearea. The transmittance level relationship among the color filters, thetransmittance of the color filters for displaying white is reduced ifthe yellow sub-pixel has the smallest aperture area. However, in thiscase, the color temperature of the light source needs to be furtherdecreased in order to maximize the chromaticity of white. If the colortemperature is further reduced, the lightness of red can be furtherincreased and the light-emitting efficiency of the light source can befurther increased. As a result, the lightness of white displayed by thedisplay device can be further increased with the increase in thelight-emitting efficiency of the light source.

A preferred embodiment of the present invention provide a display deviceincluding a display surface, the display surface including a pixelhaving red, green, blue, and yellow sub-pixels, wherein the red and bluesub-pixels have the largest aperture area (hereinafter, also referred toas “the second display device”). According to this, the red and bluesub-pixels each of which has a color filter with a low transmittancehave the largest aperture area. Therefore, the transmittance of thecolor filters for displaying white is reduced. However, in this case,the light-emitting efficiency of the light source needs to be furtherincreased in order to maximize the chromaticity of white. As a result,the lightness of white displayed by the display device can be furtherimproved with the increase of the light-emitting efficiency of the lightsource.

The configuration of a second display device according to a preferredembodiment of the present invention is not especially limited. Thesecond display device may or may not include other components as long asit includes, as a component, the above-mentioned display surfaceincluding the pixels each having the red, green, blue, and yellowsub-pixels. According to the second display device according to apreferred embodiment of the present invention, the aperture area sizerelationship among the sub-pixels in the pixel is not especially limitedas long as the red and blue sub-pixels have the same and largestaperture area and each of the sub-pixels other than the red and bluesub-pixels has an aperture area smaller than that of the red and bluesub-pixels. The pixel may include a magenta sub-pixel, in addition tored, green, blue, and yellow sub-pixels. However, it is preferable thatthe pixel includes only red, green, blue, and yellow sub-pixels in viewof a transmittance of the color filters for displaying white.

The second display device according to a preferred embodiment of thepresent invention is not especially limited. A liquid crystal displaydevice (LCD), a cathode ray tube (CRT), an organic electroluminescentdisplay device (OELD), a plasma display panel (PDP), and a fieldemission display (FED) such as a surface-conduction electron-emitterdisplay (SED) may be mentioned, for example. It is preferable that the asecond display device according to a preferred embodiment of the presentinvention performs display using a light source device such as, forexample, a backlight and/or a front light, because of the same reason asmentioned in the first display device according to a preferredembodiment of the present invention. It is more preferable that thesecond display device according to a preferred embodiment of the presentinvention is one of a transmissive liquid crystal display device whichperforms display using a backlight, a reflective liquid crystal displaydevice which performs display using a front light, or a transflectiveliquid crystal display device which performs transmissive display usinga backlight and performs reflective display using external light and/ora front light.

The second display device according to a preferred embodiment of thepresent invention is described below in more detail.

The following preferred embodiments are embodiments in which the red andblue sub-pixels have the largest aperture area. (1A) A preferredembodiment in which in the pixel, each of the red and blue sub-pixels isthe largest in number; (1B) a preferred embodiment in which in theabove-mentioned (1A), the pixel includes blue sub-pixels different incolor characteristics; (1C) a preferred embodiment in which in theabove-mentioned (1A), the pixel includes red sub-pixels different incolor characteristics; (1D) a preferred embodiment in which the greenand yellow sub-pixels have the smallest aperture area; (1E) a preferredembodiment in which the green sub-pixel has the smallest aperture area;and (1F) a preferred embodiment in which the yellow sub-pixel has thesmallest aperture area.

According to the above-mentioned preferred embodiment (1A), the aperturearea of the respective sub-pixels is the same and therefore, commonpixel and circuit designs can be adopted. In the present description,the above-mentioned “in the pixel, each of the red and blue sub-pixelsis the largest in number” means that the number of the red sub-pixeldefining a pixel and the number of the blue sub-pixel defining the pixelare the same and largest and that the number of each sub-pixel otherthan the red and blue sub-pixels is smaller than the number of each ofthe red and blue sub-pixels. According to the above-mentioned preferredembodiments (1B) and (1C), the color reproduction range can be furtherextended and the number of displayed color can be increased. In thepresent description, the phrase “different in color characteristics”means a difference in at least one of three attributes of color, i.e.,hue, lightness, and chroma. In order to extend the color reproductionrange with efficiency, the difference is a hue difference, preferably.According to the above-mentioned preferred embodiment (1D), thetransmittance of the color filters for displaying white is decreased,but the transmittance of a blue component is relatively increased.Accordingly, a blue component of light with a low light-emittingefficiency can be reduced in order to maximize the chromaticity ofwhite, and in such a case, the light-emitting efficiency of the lightsource is increased. As a result, the lightness of white displayed bythe display device can be effectively improved with the increase in thelight-emitting efficiency of the light source. According to theabove-mentioned preferred embodiment (1E), the transmittance of thecolor filters for displaying white is reduced, but the transmittance ofa blue component is relatively increased. Accordingly, a blue componentof the light source with a low light-emitting efficiency can be reducedin order to maximize the chromaticity of white, and in such a case, thelight-emitting efficiency of the light source is increased. As a result,the lightness of white displayed by the display device can be furtherimproved with the increase in the light-emitting efficiency of the lightsource. According to the above-mentioned preferred embodiment (1F), thetransmittance of the color filters for displaying white is furtherreduced, but the transmittance of a blue component is relativelyincreased, in comparison to the above-mentioned preferred embodiment(1E). Accordingly, a blue component of the light source with a lowlight-emitting efficiency can be reduced in order to maximize thechromaticity of white. If the blue component is reduced, thelight-emitting efficiency of the light source is increased. As a result,the lightness of white displayed by the display device can beparticularly improved with the increase in the light-emitting efficiencyof the light source.

Preferred embodiments of the present invention also include a displaydevice including a display surface, the display surface including apixel having red, green, blue, and yellow sub-pixels, wherein the bluesub-pixel has the largest aperture area (hereinafter, also referred toas “the third display device”). According to this, the blue sub-pixelhaving the color filter with a low transmittance has the largestaperture area. Therefore, the transmittance of the color filters fordisplaying white is reduced. However, the color temperature of the lightsource needs to be decreased in order to maximize the chromaticity ofwhite. If the color temperature of the light source is decreased, thelightness of red and the light-emitting efficiency of the light sourcecan be increased. As a result, the lightness of white displayed by thedisplay device can be improved with the increase in the light-emittingefficiency of the light source.

The configuration of a third display device according to a preferredembodiment of the present invention is not especially limited. The thirddisplay device may or may not include other components as long as itincludes, as a component, the above-mentioned display surface includingthe pixels each having the red, green, blue, and yellow sub-pixels.According to the third display device according to a preferredembodiment of the present invention, the aperture area size relationshipamong the sub-pixels defining the pixel is not especially limited aslong as the blue sub-pixel has the largest aperture area and each thesub-pixels other than the blue sub-pixel has an aperture area smallerthan that of the blue sub-pixel. The pixel may include a magentasub-pixel, in addition to the red, green, blue, and yellow sub-pixels.However, it is preferable that the pixel includes only the red, green,blue, and yellow sub-pixels in view of the transmittance of the colorfilters for displaying white.

The third display device according to a preferred embodiment of thepresent invention is not especially limited. A liquid crystal displaydevice (LCD), a cathode ray tube (CRT), an organic electroluminescentdisplay device (OELD), a plasma display panel (PDP), and a fieldemission display (FED) such as a surface-conduction electron-emitterdisplay (SED) may be mentioned, for example. It is preferable that thethird display device according to a preferred embodiment of the presentinvention performs display using a light source device such as, forexample, a backlight and/or a front light, because of the same reason asmentioned in the first display device according to a preferredembodiment of the present invention. It is more preferable that thethird display device according to a preferred embodiment of the presentinvention is one of a transmissive liquid crystal display device whichperforms display using a backlight, a reflective liquid crystal displaydevice which performs display using a front light, or a transflectiveliquid crystal display device which performs transmissive display usinga backlight and performs reflective display using external light and/ora front light.

The following preferred embodiments are mentioned as the preferredembodiment in which the blue sub-pixel has the largest aperture areainclude: (2A) a preferred embodiment in which in the pixel, the bluesub-pixel is the largest in number; and (2B) a preferred embodiment inwhich in the above-mentioned (2A), the pixel includes blue sub-pixelsdifferent in color characteristics. According to the above-mentionedpreferred embodiment (2A), the aperture area of the respectivesub-pixels is the same, and therefore, common pixel and circuit designscan be adopted. According to the above-mentioned preferred embodiment(2B), the color reproduction range can be further extended and thenumber of displayed color can be increased.

Other preferred embodiments of the third display device of the presentinvention are mentioned below in more detail.

It is preferable that the red, green, and yellow sub-pixels have thesmallest aperture area. That is, it is preferable that the red, green,and yellow sub-pixels have the same and the smallest aperture area.According to this, the aperture areas of the red, green, and yellowsub-pixels are equivalently small. Therefore, the transmittance of thecolor filters for displaying white is decreased, but the colortemperature of the light source needs to be reduced in order to maximizethe chromaticity of white. If the color temperature of the light sourceis reduced, the lightness of red can be effectively improved and thelight-emitting efficiency of the light source can be increased. As aresult, the lightness of white displayed by the display device can beincreased with the increase in the light-emitting efficiency of thelight source.

It is preferable that the pixel has a sub-pixel whose aperture area issmaller than an aperture area of the red sub-pixel. If the red sub-pixelhas the smallest aperture area, the lightness of red is decreased. As aresult, the visibility might be deteriorated. Accordingly, the redsub-pixel is arranged not to have the smallest aperture area, andthereby the reduction in lightness of red is minimized and thevisibility can be secured.

It is preferable that the green and yellow sub-pixels have the smallestaperture area. That is, it is preferable that the above-mentioned greenand yellow sub-pixels have the same and the smallest aperture area.According to this, the transmittance of the color filters for displayingwhite is decreased, but the transmittance of a blue component whichpasses through the color filter is relatively increased. Accordingly, ablue component of the light source with a low light-emitting efficiencycan be reduced in order to maximize the chromaticity of white display.If the blue component is reduced, the light-emitting efficiency of thelight source is increased. As a result, the lightness of white displayedby the display device can be improved with the increase in thelight-emitting efficiency of the light source.

It is preferable that the green sub-pixel has the smallest aperturearea. As shown in the above-mentioned transmittance level relationshipamong the color filters, if the green sub-pixel has the smallestaperture area, the transmittance of the color filters for displayingwhite is decreased, but the color temperature of the light source needsto be reduced in order to maximize the chromaticity of white. If thecolor temperature of the light source is reduced, the light-emittingefficiency of the light source is increased. As a result, the lightnessof white displayed by the display device can be improved with theincrease in the light-emitting efficiency of the light source.

It is preferable that the yellow sub-pixel has the smallest aperturearea. As shown in the above-mentioned transmittance level relationshipamong the color filters, if the yellow sub-pixel has the smallestaperture area, the transmittance of the color filters for displayingwhite is decreased, but the color temperature of the light source needsto be reduced in order to maximize the chromaticity of white. If thecolor temperature of the light source is decreased, the lightness of redcan be improved and also the light-emitting efficiency of the lightsource is further increased. Therefore, the transmittance of the colorfilters for displaying white is decreased, but the lightness of whitedisplayed by the display device can be further improved with theincrease in the light-emitting efficiency of the light source.

Preferred embodiments of the present invention further provide a displaydevice including a display surface, the display surface including apixel having red, green, blue, and yellow sub-pixels, wherein the yellowsub-pixel has the smallest aperture area (hereinafter, also referred toas “the fourth display device”). According to this, as shown in thetransmittance level relationship among the color filters, thetransmittance of the color filters for displaying white is decreased,but the color temperature of the light source needs to be reduced inorder to maximize the chromaticity of white. If the color temperature isreduced, the lightness of red can be improved and the light-emittingefficiency of the light source can be increased. As a result, thelightness of white can be improved with the increase in thelight-emitting efficiency of the light source.

The configuration of a fourth display device according to a preferredembodiment of the present invention is not especially limited. Thefourth display device may or may not include other components as long asit includes, as a component, the above-mentioned display surfaceincluding the pixels each having the red, green, blue, and yellowsub-pixels. According to the fourth display device according to apreferred embodiment of the present invention, the relationship of theaperture area size among the sub-pixels in the pixel is not especiallylimited as long as the yellow has the smallest aperture area and each ofthe sub-pixels other than the yellow sub-pixel has an aperture arealargest than the aperture area of the yellow sub-pixel. The pixel mayinclude a magenta sub-pixel, in addition to the red, green, blue, andyellow sub-pixels. However, it is preferable that the pixel includesonly the red, green, blue, and yellow sub-pixels in view of thetransmittance in the color filters used for displaying white.

The fourth display device according to a preferred embodiment of thepresent invention is not especially limited. A liquid crystal displaydevice (LCD), a cathode ray tube (CRT), an organic electroluminescentdisplay device (OELD), a plasma display panel (PDP), and a fieldemission display (FED) such as a surface-conduction electron-emitterdisplay (SED) may be included, for example. It is preferable that thefourth display device according to a preferred embodiment of the presentinvention performs display using a light source device such as, forexample, a backlight and/or a front light, because of the same reasonmentioned in the first display device according to a preferredembodiment of the present invention. It is more preferable that thefourth display device according to a preferred embodiment of the presentinvention is one of a transmissive liquid crystal display device whichperforms display using a backlight, a reflective liquid crystal displaydevice which performs display using a front light, or a transflectiveliquid crystal display device which performs transmissive display usinga backlight and performs reflective display using external light and/ora front light.

Preferred embodiments of the fourth display device of the presentinvention are described below in more detail.

It is preferable that the red, green, and blue sub-pixels have thelargest aperture area. That is, it is preferable that the red, green,and blue sub-pixels have the same and largest aperture area. Thus, thered sub-pixel has a largest aperture area and the yellow sub-pixel has asmall aperture area, and therefore, a light source with a highlight-emitting efficiency can be used. Therefore, the lightness of redand white can be effectively improved. The following preferredembodiments are mentioned as the preferred embodiment in which the red,green, and blue sub-pixels have the largest aperture area: (3A) Apreferred embodiment in which in the pixel, each of the red, green, andblue sub-pixels is the largest in number; (3B) a preferred embodiment inwhich the pixel includes blue sub-pixels different in colorcharacteristics; and (3C) a preferred embodiment in which the pixelincludes red sub-pixels different in color characteristics. According toany of the above-mentioned preferred embodiments (3A), (3B), and (3C),the aperture area of the respective sub-pixels is the same andtherefore, common pixel and circuit designs can be adopted. According tothe above-mentioned preferred embodiments (3B) and (3C), the colorreproduction range can be further extended and the number of displayedcolor can be increased.

It is preferable that the pixel includes a sub-pixel whose aperture areais larger than an aperture area of the blue sub-pixel. According to thethird display device according to a preferred embodiment of the presentinvention, the lightness of white displayed by the display device mightbe remarkably reduced. This is because the yellow sub-pixel having acolor filter with a large transmittance has the smallest aperture areaand because the blue sub-pixel having a color filter with a smalltransmittance has the largest aperture area. Accordingly, if the bluesub-pixel does not have the largest aperture area, such a reduction inlightness of white displayed by the display device can be minimized.

It is preferable that the red and green sub-pixels have the largestaperture area. That is, it is preferable that the red and greensub-pixels have the same and the largest aperture area. According tothis, the red sub-pixel has the largest aperture area, and therefore thelightness of red can be improved. The red sub-pixel has the largestaperture area, and therefore, the color temperature of the light sourceneeds to be increased in order to maximize the chromaticity of white. Ifthe color temperature of the light source is increased, thelight-emitting efficiency of the light source is reduced. However,according to preferred embodiments of the present invention, the greensub-pixel having a color filter with a large transmittance also has thelargest aperture area. As a result, the reduction in lightness of whitedisplayed by the display device can be minimized. The followingpreferred embodiments are mentioned as the preferred embodiment in whichthe red and green sub-pixels have the largest aperture area: (4A) Apreferred embodiment in which in the pixel, each of the red and greensub-pixels is the largest in number; and (4B) a preferred embodiment inwhich the pixel includes green sub-pixels different in colorcharacteristics. In both of the above-mentioned preferred embodiments(4A) and (4B), the aperture area of the respective sub-pixels is thesame and therefore, common pixel and circuit designs can be adopted.According to the above-mentioned preferred embodiment (4B), the colorreproduction range can be further extended and the number of displayedcolor can be increased.

Preferred embodiments of the present invention also include a displaydevice including a display surface, the display surface including apixel having red, green, blue, and yellow sub-pixels, wherein the red,blue, green, and yellow sub-pixels are ranked in descending order ofaperture area (hereinafter, also referred to as “the fifth displaydevice”). According to a fifth display device according to preferredembodiments of the present invention, the red sub-pixel has a largeaperture area, and therefore, the effect of improving the lightness ofred is large. In addition, the blue sub-pixel has a relatively largeaperture area and the yellow sub-pixel has a small aperture area.Therefore, a light source having a high light-emitting efficiency can beused in order to maximize the chromaticity of white. Accordingly, thelightness of red can be improved at a relatively small aperture arearatio. As a result, the reduction in lightness of white can bepreferably minimized.

The configuration of the fifth display device according to a preferredembodiment of the present invention is not especially limited. The fifthdisplay device may or may not include other components as long as itincludes, as a component, the above-mentioned display surface includingthe pixels each having the red, green, blue, and yellow sub-pixels. Thepixel may include a magenta sub-pixel, in addition to the red, green,blue, and yellow sub-pixels. However, it is preferable that the pixelincludes only the red, green, blue, and yellow sub-pixels in view of thetransmittance of the color filters for displaying white.

The fifth display device according to a preferred embodiment of thepresent invention is not especially limited. A liquid crystal displaydevice (LCD), a cathode ray tube (CRT), an organic electroluminescentdisplay device (OELD), a plasma display panel (PDP), and a fieldemission display (FED) such as a surface-conduction electron-emitterdisplay (SED) may be mentioned, for example. It is preferable that thefifth display device according to a preferred embodiment of the presentinvention performs display using a light source device such as, forexample, a backlight and/or a front light, because of the same reasonmentioned with respect to the first display device according to apreferred embodiment of the present invention. It is more preferablethat the fifth display device according to a preferred embodiment of thepresent invention is one of a transmissive liquid crystal display devicewhich performs display using a backlight, a reflective liquid crystaldisplay device which performs display using a front light, or atransflective liquid crystal display device which performs transmissivedisplay using a backlight and performs reflective display using externallight and/or a front light.

Preferred embodiments of the present invention further provide a displaydevice including a display surface, the display surface including apixel having red, green, blue, and yellow sub-pixels, wherein the red,blue, yellow, and green sub-pixels are ranked in descending order ofaperture area (hereinafter, also referred to as “the sixth displaydevice”). According to the sixth display device according to a preferredembodiment of the present invention, the red sub-pixel has a largeaperture area, and therefore the effect of improving the lightness ofred is large. In addition, the blue sub-pixel has a relatively largeaperture area and the yellow sub-pixel has a relatively small aperturearea. Therefore, a light having a high light-emitting efficiency can beused in order to maximize the chromaticity of white. As a result, thelightness of red can be improved at a relatively small aperture arearatio. As a result, the reduction in lightness of white can bepreferably minimized.

The configuration of the sixth display device according to a preferredembodiment of the present invention is not especially limited. The sixthdisplay device may or may not include other components as long as itincludes, as a component, the above-mentioned display surface includingthe pixels each having the red, green, blue, and yellow sub-pixels. Thepixel may include a magenta sub-pixel, in addition to red, green, blue,and yellow sub-pixels. However, it is preferable that the pixel includesonly the red, green, blue, and yellow sub-pixels in view of thetransmittance of the color filters for displaying white.

The sixth display device according to a preferred embodiment of thepresent invention is not especially limited. A liquid crystal displaydevice (LCD), a cathode ray tube (CRT), an organic electroluminescentdisplay device (OELD), a plasma display panel (PDP), and a fieldemission display (FED) such as a surface-conduction electron-emitterdisplay (SED) may be mentioned, for example. It is preferable that thesixth display device according to a preferred embodiment of the presentinvention performs display using a light source device such as, forexample, a backlight and/or a front light, based on the same reasonmentioned in the first display device according to a preferredembodiment of the present invention. It is more preferable that thesixth device according to a preferred embodiment of the presentinvention is one of a transmissive liquid crystal display device whichperforms display using a backlight; a reflective liquid crystal displaydevice which performs display using a front light; or a transflectiveliquid crystal display device which performs transmissive display usinga backlight and performs reflective display using external light and/ora front light.

Preferred embodiments of the present invention further include a displaydevice including a display surface, the display surface including apixel having red, green, blue, and yellow sub-pixels, wherein the red,green, blue, and yellow sub-pixels are ranked in descending order ofaperture area (hereinafter, also referred to as “the seventh displaydevice”). According to the seventh display device according to apreferred embodiment of the present invention, the red sub-pixel has alarge aperture area, and therefore the effect of improving the lightnessof red is large. In addition, the yellow sub-pixel has a small aperturearea. Therefore, a light having a high light-emitting efficiency can beused in order to maximize the chromaticity of white. Accordingly, thelightness of red can be improved at a relatively small aperture arearatio. As a result, the reduction in lightness of white can preferablybe minimized.

The configuration of the seventh display device according to a preferredembodiment of the present invention is not especially limited. Theseventh display device may or may not include other components as longas it includes, as a component, the above-mentioned display surfaceincluding the pixels each having the red, green, blue, and yellowsub-pixels. The pixel may include a magenta sub-pixel, in addition tored, green, blue, and yellow sub-pixels. However, it is preferable thatthe pixel includes only the red, green, blue, and yellow sub-pixels inview of the transmittance of the color filters for displaying white.

The seventh display device according to a preferred embodiment of thepresent invention is not especially limited. A liquid crystal displaydevice (LCD), a cathode ray tube (CRT), an organic electroluminescentdisplay device (OELD), a plasma display panel (PDP), and a fieldemission display (FED) such as a surface-conduction electron-emitterdisplay (SED) may be mentioned, for example. It is preferable that theseventh display device according to a preferred embodiment of thepresent invention performs display using a light source device such as,for example, a backlight and/or a front light, based on the same reasonmentioned in the first display device according to a preferredembodiment of the present invention. It is more preferable that theseventh display device according to a preferred embodiment of thepresent invention is one of a transmissive liquid crystal display devicewhich performs display using a backlight; a reflective liquid crystaldisplay device which performs display using a front light; or atransflective liquid crystal display device which performs transmissivedisplay using a backlight and performs reflective display using externallight and/or a front light.

Preferred embodiments of the present invention include a display deviceincluding a display surface, the display surface including a pixelhaving red, green, blue, and yellow sub-pixels, wherein the red, blue,and yellow and green sub-pixels are ranked in descending order ofaperture area (hereinafter, also referred to as “the eighth displaydevice”). The above-mentioned phrase “the red, blue, and yellow andgreen sub-pixels are ranked in descending order of aperture area” meansthat the red sub-pixel has the largest aperture area, and the yellow andgreen sub-pixels have the same and smallest aperture area, and the bluehas an aperture area that is smaller than that of the red sub-pixel andlarger than that of the yellow and green sub-pixels. According to aneighth display device according to a preferred embodiment of the presentinvention, the red sub-pixel has a large aperture area, and thereforethe effect of improving the lightness of red is large. In addition, theblue sub-pixel has a relatively large aperture area, and the yellow andgreen sub-pixels have small aperture areas. Therefore, a light having ahigh light-emitting efficiency can be used in order to maximize thechromaticity of white. Accordingly, the lightness of red can be improvedat a relatively small aperture area ratio. As a result, the reduction inlightness of white can be preferably minimized.

The configuration of the eighth display device according to a preferredembodiment of the present invention is not especially limited. Theeighth display device may or may not include other components as long asit includes, as a component, the above-mentioned display surfaceincluding the pixels each having the red, green, blue, and yellowsub-pixels. The pixel may include a magenta sub-pixel of magenta, inaddition to red, green, blue, and yellow sub-pixels. However, it ispreferable that the pixel includes only red, green, blue, and yellowsub-pixels in view of the transmittance of the color filters fordisplaying white.

The eighth display device according to a preferred embodiment of thepresent invention is not especially limited. A liquid crystal displaydevice (LCD), a cathode ray tube (CRT), an organic electroluminescentdisplay device (OELD), a plasma display panel (PDP), and a fieldemission display (FED) such as a surface-conduction electron-emitterdisplay (SED) may be mentioned, for example. It is preferable that theeighth display device according to a preferred embodiment of the presentinvention performs display using a light source device such as, forexample, a backlight and/or a front light, because of the same reasonmentioned in the first display device according to a preferredembodiment of the present invention. It is more preferable that theeighth device according to a preferred embodiment of the presentinvention is one of a transmissive liquid crystal display device whichperforms display using a backlight; a reflective liquid crystal displaydevice which performs display using a front light; or a transflectiveliquid crystal display device which performs transmissive display usinga backlight and performs reflective display using external light and/ora front light.

Preferred embodiments of the present invention further provide a displaydevice including a display surface, the display surface including apixel having red, green, blue, and yellow sub-pixels, wherein the blue,red, green, and yellow sub-pixels are ranked in descending order ofaperture area (hereinafter, also referred to as “the ninth displaydevice”). According to a ninth display device according to a preferredembodiment of the present invention, the red sub-pixel has a relativelylarge aperture area, and therefore the effect of improving the lightnessof red is large. In addition, the blue sub-pixel has a large aperturearea and the yellow sub-pixel has a smallest aperture area. Therefore, alight source having a high light-emitting efficiency can be used inorder to maximize the chromaticity of white. Accordingly, the lightnessof red can be improved at a relatively small aperture area ratio. As aresult, the reduction in lightness of white can be preferably minimized.

The configuration of the ninth display device according to a preferredembodiment of the present invention is not especially limited. The ninthdisplay device may or may not include other components as long as itincludes, as a component, the above-mentioned display surface includingthe pixels each having the red, green, blue, and yellow sub-pixels. Thepixel may include a magenta sub-pixel of magenta, in addition to red,green, blue, and yellow sub-pixels. However, it is preferable that thepixel includes only red, green, blue, and yellow sub-pixels in view ofthe transmittance of the color filters for displaying white.

The ninth display device according to a preferred embodiment of thepresent invention is not especially limited. A liquid crystal displaydevice (LCD), a cathode ray tube (CRT), an organic electroluminescentdisplay device (OELD), a plasma display panel (PDP), and a fieldemission display (FED) such as a surface-conduction electron-emitterdisplay (SED) may be mentioned, for example. It is preferable that theninth display device according to a preferred embodiment of the presentinvention performs display using a light source device such as, forexample, a backlight and/or a front light, because of the same reasonmentioned in the first display device according to a preferredembodiment of the present invention. It is more preferable that theninth device of the present invention is one of a transmissive liquidcrystal display device which performs display using a backlight; areflective liquid crystal display device which performs display using afront light; or a transflective liquid crystal display device whichperforms transmissive display using a backlight and performs reflectivedisplay using external light and/or a front light.

Preferred embodiments of the present invention further include a displaydevice including a display surface, the display surface including apixel having red, green, blue, and yellow sub-pixels, wherein the blue,red, yellow, and green sub-pixels are ranked in descending order ofaperture area (hereinafter, also referred to as “the tenth displaydevice”). According to a tenth display device according to a preferredembodiment of the present invention, the red sub-pixel has a relativelylarge aperture area, and therefore the effect of improving the lightnessof red is large. In addition, the blue sub-pixel has a large aperturearea and the yellow sub-pixel has a relatively small aperture area.Therefore, a light source having a high light-emitting efficiency can beused in order to maximize the chromaticity of white. Accordingly, thelightness of red can be improved at a small aperture area ratio. As aresult, the reduction in lightness of white can be preferably minimized.

The configuration of the tenth display device according to a preferredembodiment of the present invention is not especially limited. The tenthdisplay device may or may not include other components as long as itincludes, as a component, the above-mentioned display surface includingthe pixels each having red, green, blue, and yellow sub-pixels. Thepixel may include a magenta sub-pixel of magenta, in addition to red,green, blue, and yellow sub-pixels. However, it is preferable that thepixel includes only red, green, blue, and yellow sub-pixels in view ofthe transmittance of the color filters for displaying white.

The tenth display device according to a preferred embodiment of thepresent invention is not especially limited. A liquid crystal displaydevice (LCD), a cathode ray tube (CRT), an organic electroluminescentdisplay device (OELD), a plasma display panel (PDP), and a fieldemission display (FED) such as a surface-conduction electron-emitterdisplay (SED) may be mentioned, for example. It is preferable that thetenth display device according to a preferred embodiment of the presentinvention performs display using a light source device such as, forexample, a backlight and/or a front light, because of the same reasonmentioned in the first display device according to a preferredembodiment of the present invention. It is more preferable that thetenth device of the present invention is one of a transmissive liquidcrystal display device which performs display using a backlight; areflective liquid crystal display device which performs display using afront light; or a transflective liquid crystal display device whichperforms transmissive display using a backlight and performs reflectivedisplay using external light and/or a front light.

Preferred embodiments of the present invention also include a displaydevice including a display surface, the display surface including apixel having red, green, blue, and yellow sub-pixels, wherein the blue,green, red, and yellow sub-pixels are ranked in descending order ofaperture area (hereinafter, also referred to as “the eleventh displaydevice”). According to an eleventh display device according to apreferred embodiment of the present invention, the yellow sub-pixel hasa particularly small aperture area. Therefore, a red component can beemitted at a higher intensity from a backlight and the like, and in sucha case, an effect of improving the lightness of red is large. Inaddition, the blue sub-pixel has a large aperture area and the yellowsub-pixel has a small aperture area. Therefore, a light source having ahigh light-emitting efficiency can be used in order to maximize thechromaticity of white. Accordingly, the lightness of red can be improvedat a relatively small aperture area ratio. As a result, the reduction inlightness of white can be preferably minimized.

The configuration of the eleventh display device according to apreferred embodiment of the present invention is not especially limited.The eleventh display device may or may not include other components aslong as it includes, as a component, the above-mentioned display surfaceincluding the pixels each having red, green, blue, and yellowsub-pixels. The pixel may include a magenta sub-pixel of magenta, inaddition to red, green, blue, and yellow sub-pixels. However, it ispreferable that the pixel includes only red, green, blue, and yellowsub-pixels in view of the transmittance of the color filters fordisplaying white.

The eleventh display device according to a preferred embodiment of thepresent invention is not especially limited. A liquid crystal displaydevice (LCD), a cathode ray tube (CRT), an organic electroluminescentdisplay device (OELD), a plasma display panel (PDP), and a fieldemission display (FED) such as a surface-conduction electron-emitterdisplay (SED) may be mentioned, for example. It is preferable that theeleventh display device according to a preferred embodiment of thepresent invention performs display using a light source device such as,for example, a backlight and/or a front light, based on the same reasonmentioned in the first display device according to a preferredembodiment of the present invention. It is more preferable that theeleventh device of the present invention is one of a transmissive liquidcrystal display device which performs display using a backlight; areflective liquid crystal display device which performs display using afront light; or a transflective liquid crystal display device whichperforms transmissive display using a backlight and performs reflectivedisplay using external light and/or a front light.

Preferred embodiments of the present invention also include a displaydevice including a display surface, the display surface including apixel having red, green, blue, and yellow sub-pixels, wherein the blueand green, red, and yellow sub-pixels are ranked in descending order ofaperture area (hereinafter, also referred to as “the twelfth displaydevice”). The above-mentioned “the blue and green, red, and yellowsub-pixels are ranked in descending order of aperture area” means thatthe blue and green sub-pixels have the same and largest aperture area,and the yellow sub-pixel has the smallest aperture area, and the redsub-pixel has an aperture area smaller than the aperture areas of theblue and green sub-pixels and larger than the aperture area of theyellow sub-pixel. According to a twelfth display device according to apreferred embodiment of the present invention, the yellow sub-pixel hasa particularly small aperture area. Therefore, a red component can beemitted at a higher intensity from a backlight and the like, and in sucha case, an effect of improving the lightness of red is large. Inaddition, the blue sub-pixel has a large aperture area and the yellowsub-pixel has a small aperture area. Further, a light source having ahigh light-emitting efficiency can be used in order to maximize thechromaticity of white. Accordingly, the lightness of red can be improvedat a relatively small aperture area ratio. As a result, the reduction inlightness of white can preferably be minimized.

The configuration of the twelfth display device according to a preferredembodiment of the present invention is not especially limited. Thetwelfth display device may or may not include other components as longas it includes, as a component, the above-mentioned display surfaceincluding the pixels each having red, green, blue, and yellowsub-pixels. The pixel may include a magenta sub-pixel of magenta, inaddition to red, green, blue, and yellow sub-pixels. However, it ispreferable that the pixel includes only red, green, blue, and yellowsub-pixels in view of the transmittance of the color filters fordisplaying white.

The twelfth display device according to a preferred embodiment of thepresent invention is not especially limited. A liquid crystal displaydevice (LCD), a cathode ray tube (CRT), an organic electroluminescentdisplay device (OELD), a plasma display panel (PDP), and a fieldemission display (FED) such as a surface-conduction electron-emitterdisplay (SED) may be mentioned, for example. It is preferable that thetwelfth display device according to a preferred embodiment of thepresent invention performs display using a light source device such as,for example, a backlight and/or a front light, because of the samereason mentioned in the first display device according to a preferredembodiment of the present invention. It is more preferable that thetwelfth device according to a preferred embodiment of the presentinvention is one of a transmissive liquid crystal display device whichperforms display using a backlight; a reflective liquid crystal displaydevice which performs display using a front light; or a transflectiveliquid crystal display device which performs transmissive display usinga backlight and performs reflective display using external light and/ora front light.

According to display devices according to various preferred embodimentsof the present invention, the pixel includes a sub-pixel for displayingyellow, in addition to sub-pixels for displaying red, green, and blue,respectively. The display device of the present invention performsdisplay using more than three primary colors. Therefore, it can displayan image with a wider color reproduction range in comparison to adisplay device which performs display using three primary colors. Inaddition, the sub-pixel for displaying red is the largest, and thereforethe lightness of red can be improved.

Other features, elements, steps, characteristics and advantages of thepresent invention will become more apparent from the following detaileddescription of preferred embodiments of the present invention withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a planar view schematically showing the TFT substrate in theliquid crystal display device in accordance with a preferred embodiment1 of the present invention.

FIG. 2 is a planar view schematically showing the counter substrate inthe liquid crystal display device in accordance with preferredembodiment 1 of the present invention.

FIG. 3 is a cross-sectional view schematically showing the liquidcrystal display device in accordance with preferred embodiment 1 of thepresent invention.

FIG. 4 is a view showing spectral transmittance characteristics of aliquid crystal layer.

FIG. 5 is a planar view schematically showing a display surface of theliquid crystal display device in accordance with preferred embodiment 1of the present invention.

FIG. 6 is a planar view schematically showing a display surface of theliquid crystal display device in accordance with preferred embodiment 1of the present invention.

FIG. 7 is a diagram showing spectral transmittance characteristics ofthe color filters.

FIG. 8 is a diagram showing spectral characteristics of a light sourceof a back light, used in the liquid crystal display device (the liquidcrystal display device A6 in Table 3) in accordance with preferredembodiment 1 of the present invention.

FIG. 9 is a diagram showing spectral characteristics of a light sourceof a backlight, used in a conventional three-primary-color liquidcrystal display device.

FIG. 10 is a diagram showing a relationship between a lightness of redand a lightness of white displayed by the liquid crystal display devicein accordance with preferred embodiment 1 of the present invention.

FIG. 11 is a view schematically showing a modified example of thedisplay surface of the liquid crystal display device in accordance withpreferred embodiment 1 of the present invention.

FIG. 12 is a view schematically showing a modified example of thedisplay surface of the liquid crystal display device in accordance withpreferred embodiment 1 of the present invention.

FIG. 13 is a diagram showing spectral transmittance characteristics ofthe color filters.

FIG. 14 is a view schematically showing a display surface of the liquidcrystal display device in accordance with a preferred embodiment 2 ofthe present invention.

FIG. 15 is a view schematically showing a display surface of the liquidcrystal display device in accordance with preferred embodiment 2 of thepresent invention.

FIG. 16 is a diagram schematically showing a relationship between alightness of red and a lightness of white displayed by the liquidcrystal display device in accordance with preferred embodiment 2 of thepresent invention.

FIG. 17 is a view schematically showing a display surface of the liquidcrystal display device in accordance with a preferred embodiment 3 ofthe present invention.

FIG. 18 is a view schematically showing a display surface of the liquidcrystal display device in accordance with preferred embodiment 3 of thepresent invention.

FIG. 19 is a diagram showing a relationship between a lightness of redand a lightness of white displayed by the liquid crystal display devicein accordance with preferred embodiment 3 of the present invention.

FIG. 20 is a view schematically showing a modified example of thedisplay surface of the liquid crystal display device in accordance withpreferred embodiment 3 of the present invention.

FIG. 21 is a view schematically showing a modified example of thedisplay surface of the liquid crystal display device in accordance withpreferred embodiment 3 of the present invention.

FIG. 22 is a diagram schematically showing spectral transmittancecharacteristics of the color filters used in the liquid crystal displaydevice in FIG. 21.

FIG. 23 is a view schematically showing a modified example of thedisplay surface of the liquid crystal display device in accordance withpreferred embodiment 3 of the present invention.

FIG. 24 is a view schematically showing a modified example of thedisplay surface of the liquid crystal display device in accordance withpreferred embodiment 3 of the present invention.

FIG. 25 is a view schematically showing a display surface of the liquidcrystal display device in accordance with a preferred embodiment 4 ofthe present invention.

FIG. 26 is a view schematically showing a display surface of the liquidcrystal display device in accordance with preferred embodiment 4 of thepresent invention.

FIG. 27 is a diagram showing a relationship between a lightness of redand a lightness of white displayed by the liquid crystal display devicein accordance with preferred embodiment 4 of the present invention.

FIG. 28 is a view schematically showing a display surface of the liquidcrystal display device in accordance with a preferred embodiment 5 ofthe present invention.

FIG. 29 is a view schematically showing a display surface of the liquidcrystal display device in accordance with preferred embodiment 5 of thepresent invention.

FIG. 30 is a diagram showing a relationship between a lightness of redand a lightness of white displayed by the liquid crystal display devicein accordance with preferred embodiment 5 of the present invention.

FIG. 31 is a view schematically showing a modified example of thedisplay surface of the liquid crystal display device in accordance withpreferred embodiment 5 of the present invention.

FIG. 32 is a view schematically showing a modified example of thedisplay surface of the liquid crystal display device in accordance withpreferred embodiment 5 of the present invention.

FIG. 33 is a view schematically showing a display surface of the liquidcrystal display device in accordance with a preferred embodiment 6 ofthe present invention.

FIG. 34 is a view schematically showing a display surface of the liquidcrystal display device in accordance with preferred embodiment 6 of thepresent invention.

FIG. 35 is a diagram showing a relationship between a lightness of redand a lightness of white displayed by the liquid crystal display devicein accordance with preferred embodiment 6 of the present invention.

FIG. 36 is a view schematically showing a display surface of aconventional four-primary-color liquid crystal display device.

FIG. 37 is a view schematically showing a display surface of aconventional three-primary-color liquid crystal display device.

FIG. 38 is a diagram showing spectral characteristics of a light sourceof a backlight used in a conventional four-primary-color display device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is mentioned in more detail below with referenceto preferred embodiments, but it is not limited to only these preferredembodiments. Configurations and measurement values and the like in thefollowing preferred embodiments are based on a simulation which isperformed using a computer program. In the following preferredembodiments, a transmissive liquid crystal display device is exemplifiedto explain the present invention.

Preferred Embodiment 1

A configuration of a liquid crystal display device in accordance withpreferred embodiment 1 of the present invention is mentioned below. Theconfiguration of the liquid crystal display device of the presentinvention is not limited to this configuration.

FIG. 1 is a planar view schematically showing a configuration of a TFTsubstrate 200 in a transmissive liquid crystal display device inaccordance with preferred embodiment 1 of the present invention. Asshown in FIG. 1, the TFT substrate 200 has the following configuration.Matrix wirings defined by scanning lines 4 and signal lines 6 arearranged on a glass substrate, for example. In each intersection of thematrix wirings, a thin film transistor (TFT) 8 is arranged. In eachregion surrounded by the matrix wirings, a transmissive electrode 35(including transmissive electrodes 35R, 35G, 35Y, and 35B) made of atransparent conductive material such as indium tin oxide (ITO) isarranged. A gate electrode of the TFT 8 is connected to the scanningline 4, and a source electrode of the TFT 8 is connected to the signalline 6. The drain electrode of the TFT 8 is connected to thetransmissive electrode 35 through a drain-extracting wiring 9. Thetransmissive electrodes 35R, 35G, 35Y, and 35B are arranged to oppose ared color filter 10R, a green color filter 10G, a blue color filter 10B,and a yellow color filter 10Y, respectively. The red, green, blue, andyellow color filters 10R, 10G, 10B, and 10Y are arranged in thebelow-mentioned color filter substrate 11 of the liquid crystal displaydevice. According to the present preferred embodiment, as shown in FIG.1, the scanning line 4 and the signal line 6 are arranged in such a waythat the transmissive electrode 35R opposing the red color filter 10R islarge and the transmissive electrodes 35G, 35Y, and 35R opposing theother color filters are equivalently small. A storage capacitor wiring 7is arranged in parallel to the scanning line 4 to maintain a voltageapplied to the transmissive electrode 35. The storage capacitor wiring 7opposes the end of the drain-extracting wiring 9 with an insulating filmtherebetween to define a storage capacitance 3.

FIG. 2 is a planar view schematically showing a configuration of thecolor filter substrate (counter substrate) 100 in the transmissiveliquid crystal display device in accordance with preferred embodiment 1of the present invention.

According to the color filter substrate 100, as shown in FIG. 2, the redcolor filter 10R, the green color filter 10G, the yellow color filter10Y, and the blue color filter 10B are arranged in a stripe pattern inthis order, and a black matrix 10BM is arranged around each filter andbetween the filters. Each of the color filters 10R, 10G, 10B, and 10Yselectively transmits light. The red color filter 10R mainly transmits ared component of incident light. The green color filter 10G mainlytransmits a green component of incident light. The blue color filter 10Bmainly transmits a blue component of incident light. The yellow colorfilter 10Y mainly transmits both of a red component and a greencomponent of incident light. In the present preferred embodiment, asshown in FIG. 2, the color filters 10R, 10B, 10G, and 10Y are arrayed inthe same pattern among all of the pixels, but may be arrayed in adifferent pattern among the pixels. The configuration of the pixel inthe present invention is not especially limited. The color filters 10R,10B, 10G, and 10R are arranged to oppose the transmissive electrodes35R, 35G, 35Y, and 35B, respectively, arranged in the above-mentionedTFT substrate 200 of the liquid crystal display device. The black matrix10BM is arranged to oppose the scanning line 4 and the signal line 6 inthe liquid crystal display device. According to the present preferredembodiment, as shown in FIG. 2, the area of the red color filter 10R islarge, and other color filters 10B, 10G, and 10Y are equivalently small.

FIG. 3 is a cross-sectional view schematically showing the transmissiveliquid crystal display device in accordance with preferred embodiment 1of the present invention.

As shown in FIG. 3, a transmissive liquid crystal display device 500 inaccordance with preferred embodiment 1 of the present invention includesa liquid crystal layer 300 between the above-mentioned color filtersubstrate 100 and the above-mentioned TFT substrate 200. The colorfilter substrate 100 includes a retarder 22 and a polarizer 23 on anouter surface side (observation surface side) of the glass substrate 21,and further includes the red color filter 10R, the green color filter10G, the blue color filter 10B, and the yellow color filter 10Y, theblack matrix 10BM, and an overcoat layer 25, a counter electrode 26, andan alignment film 27 on an inner surface side (back surface side) of theglass substrate 21.

The retarder 22 adjusts a polarization state of light which passesthrough the retarder 22. The polarizer 23 transmits only light having aspecific polarization component. According to the present preferredembodiment, the arrangement and configuration of the retarder 22 and thepolarizer 23 are adjusted in such a way that the retarder 22 and thepolarizer 23 function as circular polarizers.

The overcoat layer 25 prevents elution of a contaminant from the red,green, blue, and yellow filters 10R, 10G, 10B, and 10Y into the liquidcrystal layer 300. Further, the overcoat layer 25 flattens the surfaceof the color filter substrate 100. The counter electrode 26 opposes thetransparent electrodes 35R, 35G, 35B, and 35Y arranged on the TFTsubstrate 200 side with the liquid crystal layer 300 therebetween. Thecounter electrode 26 is used to drive liquid crystal molecules byapplying a voltage to the liquid crystal layer 300. The counterelectrode 26 is made of a transparent conductive material such as, forexample, indium tin oxide (ITO). The alignment film 27 controlsalignment of liquid crystal molecules in the liquid crystal layer 300.

The TFT substrate 200 includes a retarder 32 and a polarizer 33 on anouter surface side (back surface side) of the glass substrate 31, andfurther includes the thin film transistor (TFT) 8, an interlayerinsulating film 34, the transparent electrode 35 (defined of thetransparent electrodes 35R, 35G, 35B, and 35Y), and an alignment film 38on an inner surface side (observation surface side) of the glasssubstrate 31.

The retarder 32 adjusts a polarization state of light which passesthrough the retarder 32, similarly to the retarder 22. The polarizer 33transmits only light having a specific polarization component, similarlyto the polarizer 23. According to the present preferred embodiment, thispolarizer 33 is arranged to be optically perpendicular or substantiallyoptically perpendicular to the circular polarizer arranged on the colorfilter substrate 100 side.

The transparent electrode 35 (defined of the transparent electrodes 35R,35G, 35B, and 35Y) is arranged in each color filter on the color filtersubstrate 100 side. In each color filter region, a voltage is applied tothe liquid crystal layer 300 to drive liquid crystal molecules. Thealignment film 38 controls alignment of the liquid crystal molecules inthe liquid crystal layer 300, similarly to the alignment film 27.

On the rear surface side (back surface side) of the TFT substrate 200, abacklight 36 is arranged to be used for display. Spectralcharacteristics and the like of a light source of the backlight 36 arementioned below. FIG. 4 is a view showing spectral characteristics ofthe liquid crystal layer 300. According to the present preferredembodiment, a nematic liquid crystal with a negative dielectricanisotropy is used as a material for the liquid crystal layer 300.

FIG. 5 is a planar view schematically showing a configuration of thepixel of the liquid crystal display device 500 in accordance withpreferred embodiment 1 of the present invention. According to thepresent preferred embodiment, the liquid crystal display device 500 hasthe above-mentioned configuration. Therefore, as shown in FIG. 5, thered sub-pixel 5Ra has the largest aperture area. The green, blue, andyellow sub-pixels 5Ga, 5Ba, and 5Ya are equivalently small. Such apreferred embodiment is mentioned below. The aperture area means an areaof a region which is actually used in displaying an image, and it doesnot include an area of a region which is shielded by the thin filmtransistors (TFT) 8, the scanning lines 4, the signal lines 6, andstorage capacitances 3, and black matrixes 10BM. The liquid crystaldisplay device 500 in accordance with the present preferred embodimentincludes a plurality of pixels 11 a arrayed in a matrix pattern. Theshaded portion in FIG. 5 corresponds to one pixel. In FIG. 5, fourpixels among the plurality of pixels 11 a defining the display surface500 a in the liquid crystal display device 500 are shown.

As shown in FIG. 5, the pixel 11 a is defined by a plurality ofsub-pixels. According to the present preferred embodiment, the foursub-pixels defining the pixel 11 a are a sub-pixel 5Ra for displayingred, a sub-pixel 5Ga for displaying green, and a sub-pixel 5Ba fordisplaying blue, and a sub-pixel 5Ya for displaying yellow. FIG. 5 showsa configuration in which these four sub-pixels are arranged in one rowand four columns in the pixel 11 a. FIG. 6 shows another configurationof a pixel defining a screen surface 500 b of the liquid crystal displaydevice and shows a configuration in which four sub-pixels 5Rb, 5Gb, 5Bb,and 5Yb are arranged in two rows and two columns in the pixel 11 b.According to the present preferred embodiment, the array of the red,green, blue, and yellow sub-pixels is not especially limited to thearrays shown in FIGS. 5 and 6. Attributed to the aperture area ratioamong the respective sub-pixels, the effects can be obtained.

Six liquid crystal display devices A1 to A6 shown in Table 3 areprepared in this preferred embodiment. In each of these liquid crystaldisplay devices A1 to A6, the red sub-pixel is different in aperturearea from the other sub-pixels. Specifically, the aperture area of thered sub-pixel is the largest and the aperture areas of the green, blue,and yellow sub-pixels are equivalently small.

TABLE 3 The largest Light- aperture area/ Color filter emitting Aperturearea ratio The smallest Lightness Lightness transmittance efficiency of(red:green:blue:yellow) aperture area of red (%) of white (%) backlightA1 11:9.7:9.7:9.7 1.13 12.3 97.7 39.6 0.78 A2 12:9.3:9.3:9.3 1.29 12.996.0 38.7 0.79 A3 13:9:9:9 1.44 13.4 93.3 37.7 0.78 A4 14:8.7:8.7:8.71.61 14.2 91.0 36.8 0.78 A5 15:8.3:8.3:8.3 1.81 14.9 88.6 35.8 0.78 A616:8:8:8 2.00 15.6 86.1 34.7 0.78

In all of the liquid crystal display devices A1 to A6, a color filterhaving a spectral transmittance shown in FIG. 7 is used. The aperturearea ratio among the sub-pixels varies depending on the liquid crystaldisplay devices, and therefore, the chromaticity of white displayed bythe color filter also varies depending on the liquid crystal displaydevices. In the present preferred embodiment, in order to obtain adesired chromaticity of white, a spectrum of a light source of thebacklight 36 is adjusted in each liquid crystal display device.Specifically, spectral characteristics of the light source of thebacklight 36 used in the liquid crystal display devices A1 to A6 areproperty adjusted in such a way that white displayed by the liquidcrystal display device shows chromaticity coordinates: x=0.313; andy=0.329 and that the color temperature is about 6500K. A cold cathodefluorescent tube (CCFT) is used as the light source of the backlight 36,for example. The mixing ratio among red, green, and blue fluorescentmaterials is varied to adjust spectral characteristics of the lightsource. Spectral characteristics of the light source of the backlight 36used in the liquid crystal display device A6 in Table 3 are shown inFIG. 8, as one example.

Table 3 shows an aperture area ratio among the respective sub-pixels, anaperture area ratio between the sub-pixel having the largest aperturearea (red sub-pixel) and the sub-pixel having the smallest aperture area(green, blue, or yellow sub-pixel), a lightness of red, a lightness ofwhite, an average transmittance of the color filters, and alight-emitting efficiency of the light source of the backlight, in theliquid crystal display devices A1 to A6. The lightness of red is a valuerelative to 100 of a lightness Y of white in each liquid crystal displaydevice (a ratio relative to the lightness of white). The lightness ofwhite is a value relative to 100 of a lightness of white displayed bythe following conventional four-primary-color liquid crystal displaydevice (shown in FIG. 36). According to the conventionalfour-primary-color liquid crystal display device, the sub-pixels of therespective colors have the same aperture area, a color filter having aspectral transmittance shown in FIG. 7 is used, and a CCFT havingspectral characteristics shown in FIG. 38 is used as a light source ofthe backlight 36. Further, the average transmittance of the colorfilters is an average value of transmittances in the respective colorfilters used for displaying white using the light source of thebacklight 36 arranged in each liquid crystal display device. Thelight-emitting efficiency of the light source of the backlight 36 isdetermined as follows. First, a light-emitting efficiency of a redfluorescent material used in a CCFT (light source), a light-emittingefficiency of a green fluorescent material used in a CCFT (lightsource), and a light-emitting efficiency of a blue fluorescent materialused in a CCFT (light source) are individually measured. Then, on thebasis of these measurement values, the mixing ratio among the red,green, and blue fluorescent materials is varied. Under such a condition,the light-emitting efficiency in the case where red, green, and blue arecombined is calculated. The light-emitting efficiency of the lightsource of the backlight 36 is a ratio between a light-emittingefficiency in the case where red, green, and blue are combined, and alight-emitting efficiency in the case where red, green, and blue arecombined in the conventional three-primary-color display device.

FIG. 10 is a diagram showing a relationship between a lightness of redand a lightness of white displayed by the liquid crystal display devicesA1 to A6 prepared in the present preferred embodiment.

According to the liquid crystal display devices A1 to A6 in the presentpreferred embodiment, the red sub-pixel has the largest aperture area.Therefore, the lightness of red can be more improved and brighter redcan be displayed in comparison to the conventional four-primary-colorliquid crystal display device (Table 1) shown in FIG. 36. That is, redwith excellent visibility can be displayed. An appropriate one amongthese liquid crystal display devices A1 to A6 may be selected dependingon an application and the like.

According to the present preferred embodiment, a common CCFT is used asa light source of the backlight 36. The chromaticity of white isadjusted by varying only the mixing ratio among the red, green, and bluefluorescent materials. The lightness of white displayed by the liquidcrystal display device is calculated, also taking the variation of thelight-emitting efficiency, in the case that in the light source of thebacklight, the mixing ratio among the fluorescent materials of therespective colors is varied, into consideration. That is, the lightnessof white is the lightness in the liquid crystal display device, takingnot only an average transmittance (efficiency) of the color filters butalso the light-emitting efficiency of the light source of the back light36 into consideration. In the preferred embodiments of the presentinvention, the chromaticity of white is set to the above-mentionedvalue, but it is not limited thereto. The same effect can be obtained ifthe chromaticity of white is appropriately adjusted to an optimalchromaticity.

The pixel configuration of the liquid crystal display device in thepresent preferred embodiment is not limited to those shown in FIGS. 5and 6. For example, as shown in FIG. 11, the liquid crystal displaydevice in the present preferred embodiment may have a configuration inwhich a pixel 11 c defining a display surface 500 c is divided into fivesub-pixels and two red sub-pixels are arranged. In FIG. 11, with regardto the aperture area ratio among the red sub-pixel 5Rc, the greensub-pixel 5Gc, the blue sub-pixel 5Bc, and the yellow sub-pixel 5Yc,red:green:blue:yellow is 2:1:1:1. Thus, a plurality of red sub-pixelsare arranged, and thereby an amount of modification of the pixel designand the driving circuit design can be minimized.

As shown in FIG. 12, the liquid crystal display device in the presentpreferred embodiment may have a configuration in which a pixel 11 ddefining a display surface 500 d is divided into five sub-pixels, andtwo red sub-pixels having different color characteristics are arranged.Spectral characteristics of the color filters are shown in FIG. 13. Inthis case, light having a dominant wavelength of about 612 nm passesthrough a red sub-pixel 5R₁d, and light having a dominant wavelength ofabout 607 nm passes through a red sub-pixel 5R₂d. Also in the case shownin FIG. 12, the aperture areas of the red sub-pixels 5R₁d and 5R₂d, thegreen sub-pixel 5Gd, the blue sub-pixel Bd, and the yellow sub-pixel 5Ydare equivalent. With regard to the aperture area ratio among therespective sub-pixels, red:green:blue:yellow is 2:1:1:1. Thus, the twored sub-pixels having different color characteristics are arranged, andthereby the color reproduction range can be further extended. Thesepixel configurations are just mentioned as one example, and the presentpreferred embodiment is not limited to these pixel configurations.

Preferred Embodiment 2

With regard to a transmittance level relationship among the respectivecolor filters arranged in the red, green, blue, and yellow sub-pixels,and a transmittance of the color filters for displaying white (anaverage transmittance of the red, green, blue, and yellow sub-pixels),yellow, green, white, red, and blue are ranked in descending order oftransmittance. In some cases, the red and blue are counterchanged, andyellow, green, white, blue, and red are ranked in descending order oftransmittance.

Accordingly, if the aperture area of the red sub-pixel is increased, thetransmittance of the color filters for displaying white is decreasedbecause the color filter arranged in the red sub-pixel has a smallertransmittance than that of the color filters for displaying white. Inaddition, if the aperture areas of the green and yellow sub-pixels aredecreased, the transmittance of the color filters for displaying whiteis further decreased because the color filters arranged in the green andyellow sub-pixels have a larger transmittance than that of the colorfilters for displaying white. In contrast, if the aperture area of theblue sub-pixel is decreased, the reduction in transmittance of the colorfilters for displaying white is minimized and possibly improved becausethe color filter arranged in the blue sub-pixel has the smallesttransmittance. However, this relationship is satisfied if only colorfilter is taken into consideration. Hence, in an actual liquid crystaldisplay device, the light-emitting efficiency of the light source of thebacklight needs to be taken into consideration.

In preferred embodiment 1, a certain effect in which the lightness ofred is increased is recognized if the aperture area of the red sub-pixelis the largest and the aperture areas of the green, blue, and yellowsub-pixels are equivalently small. However, in preferred embodiment 1,as shown in FIG. 10, the lightness of white is slightly reduced in allof the liquid crystal display devices A1 to A6 shown in Table 3.Accordingly, the display device in preferred embodiment 2 is superior tothat in preferred embodiment 1, if the reduction in lightness of whitecan be minimized. In the present preferred embodiment, the lightness ofwhite is also taken into consideration, and the aperture area of the redsub-pixel is increased, and the aperture area of anyone of the green,blue, and yellow sub-pixels is reduced. Such a preferred embodiment ismentioned below.

Table 4 shows an aperture area ratio among the respective sub-pixels, anaperture area ratio between the sub-pixel having the largest aperturearea (red sub-pixel) and the sub-pixel having the smallest aperture area(green sub-pixel), a lightness of red, a lightness of white, an averagetransmittance of the color filters, and a light-emitting efficiency ofthe light source of the backlight, in liquid crystal display devices B1to B6 prepared in the present preferred embodiment in the case that thered sub-pixel has a large aperture area and the blue sub-pixel has asmall aperture area.

TABLE 4 The largest Light- aperture area/ Color filter emitting Aperturearea ratio The smallest Lightness Lightness transmittance efficiency of(red:green:blue:yellow) aperture area of red (%) of white (%) backlightB1 11:9:10:10 1.22 11.7 99.7 39.5 0.80 B2 12:8:10:10 1.50 12.3 98.3 38.40.81 B3 13:7:10:10 1.86 12.8 97.3 37.2 0.83 B4 14:6:10:10 2.33 13.3 95.936.0 0.84 B5 15:5:10:10 3.00 14.0 94.7 34.8 0.86

Table 5 shows an aperture area ratio among the respective sub-pixels, anaperture area ratio between the sub-pixel having the largest aperturearea (red sub-pixel) and the sub-pixel having the smallest aperture area(blue sub-pixel), a lightness of red, a lightness of white, an averagetransmittance of the color filters, and a light-emitting efficiency ofthe light source of the backlight, in liquid crystal display devices C1to C3 prepared in the present preferred embodiment in the case that thered sub-pixel has a large aperture area and the blue sub-pixel has asmall aperture area.

TABLE 5 The largest Light- aperture area/ Color filter emitting Aperturearea ratio The smallest Lightness Lightness transmittance efficiency of(red:green:blue:yellow) aperture area of red (%) of white (%) backlightC1 11:10:9:10 1.22 11.6 95.7 40.2 0.75 C2 12:10:8:10 1.50 12.1 90.8 39.80.72 C3 13:10:7:10 1.86 12.9 84.3 39.3 0.68

Table 6 shows an aperture area ratio among the respective sub-pixels, anaperture area ratio between the sub-pixel having the largest aperturearea (red sub-pixel) and the sub-pixel having the smallest aperture area(yellow sub-pixel), a lightness of red, a lightness of white, an averagetransmittance of the color filters, and a light-emitting efficiency ofthe light source of the backlight, in liquid crystal display devices D1to D6 prepared in the present Preferred embodiment in the case that thered sub-pixel has a large aperture area and the yellow sub-pixel has asmall aperture area.

TABLE 6 The largest Light- aperture area/ Color filter emitting Aperturearea ratio The smallest Lightness Lightness transmittance efficiency of(red:green:blue:yellow) aperture area of red (%) of white (%) backlightD1 11:10:10:9 1.22 12.4 98.4 39.0 0.80 D2 12:10:10:8 1.50 13.8 96.9 37.50.82 D3 13:10:10:7 1.86 15.2 94.8 36.0 0.83 D4 14:10:10:6 2.33 16.4 92.734.4 0.85 D5 15:10:10:5 3.00 17.8 91.3 32.8 0.88 D6 16:10:10:4 4.00 19.588.9 31.2 0.90

Each of FIGS. 14 and 15 shows a schematic view of the liquid crystaldisplay device in Table 6. FIG. 14 shows a configuration of a pixel 11 edefining a display surface 500 e of the liquid crystal display device,and the pixel 11 e includes four sub-pixels 5Re, 5Ge, 5Be, and 5Yearranged in a stripe pattern. FIG. 15 shows a configuration of a pixel11 f defining a display surface 500 f of the liquid crystal displaydevice, and the pixel 11 f includes four sub-pixels 5Rf, 5Gf, 5Bf, and5Yf arranged in two rows and two columns.

FIG. 16 shows a relationship between a lightness of red and a lightnessof white displayed by the respective liquid crystal displays shown inTables 4, 5, and 6. In FIG. 16, ⋄ corresponds to the liquid crystaldisplay devices B1 to B5 in Table 4; Δ corresponds to the liquid crystaldisplay devices C1 to C3 in Table 5; and ∘ corresponds to the liquidcrystal display devices D1 to D6 in Table 6. For comparison, □ shows theliquid crystal display devices A1 to A6 in accordance with preferredembodiment 1.

As shown in FIG. 16, according to the liquid crystal display devices inTables 4 to 6, the effect of improving the lightness of red can beobserved in comparison to the conventional four-primary-color liquidcrystal display device (see Table 1) shown in FIG. 36. Particularly inthe liquid crystal display device D6 in Table 6, red having a lightnessof as high as 19.5% can be displayed. As shown in Tables 4 and 6, theaverage transmittance of the color filters is reduced in comparison tothe liquid crystal display devices A1 to A6 in preferred embodiment 1 ifthe green or yellow sub-pixel has a small aperture area. However, thespectral characteristics of the light source of the backlight areadjusted in order to maximize the chromaticity of white. As a result,the light-emitting efficiency of the light source is increased.Therefore, as shown in FIG. 16, the reduction in lightness of white canbe minimized with the increase in the light-emitting efficiency of thelight source of the backlight, in comparison to the liquid crystaldisplay devices A1 to A6 in preferred embodiment 1. Particularly in theliquid crystal display devices D1 to D6 in Table 6, if the sub-pixelhaving a small aperture area is a yellow sub-pixel having a color filterwith the highest transmittance, the average transmittance of the colorfilters is reduced, but the light-emitting efficiency of the lightsource of the backlight is increased. As a result, the reduction inlightness of white is decreased with the increase in the light source ofthe backlight.

As shown in the liquid crystal display devices C1 to C3 in Table 5, itis not preferable to reduce the aperture area of the blue sub-pixelbecause the lightness of white is largely reduced. That is, if thesub-pixel having a small aperture area is a blue sub-pixel, the averagetransmittance of the color filters is increased because the color filterarranged in the blue sub-pixel has the smallest transmittance. However,the spectral characteristics of the light source of the backlight areadjusted in order to maximize the chromaticity of white. As a result,the light-emitting efficiency of the light source is reduced. Hence, thereduction in lightness of white is increased with the decrease in thelight-emitting efficiency of the light source of the backlight.

As mentioned above, the preferred embodiment in which the yellowsub-pixel has a small aperture area is the most effective preferredembodiment, followed by the preferred embodiment in which the greensub-pixel has a small aperture area and the preferred embodiment inwhich the blue sub-pixel has a small aperture area.

The pixel design and the driving circuit design needs to be changed ifthe sub-pixels are largely different in aperture area. Therefore, it ispreferable that an aperture area ratio among the sub-pixels is as smallas possible. From viewpoint of this aperture area ratio, in the liquidcrystal display device A4 in Table 3 in accordance with preferredembodiment 1, an aperture area ratio between the red sub-pixel havingthe largest aperture area, and the green, blue, and yellow sub-pixelshaving the smallest aperture areas is 1.61:1. In this case, thelightness of red is 14.2%; the lightness of white is 91.0%. The liquidcrystal display device B5 in Table 4 in accordance with the presentpreferred embodiment can provide a lightness equivalent to 14.2% of red.According to this liquid crystal display device B5, the lightness ofwhite is 94.7%. Therefore, the liquid crystal display device B5 issuperior to the liquid crystal display device A4 in terms of thelightness of white. Further, the liquid crystal display device D3 inTable 6 in accordance with the present preferred embodiment also canprovide a lightness equivalent to 14.2% of red. According to this liquidcrystal display device D3, the lightness of white is 94.8%. Therefore,the liquid crystal display device D3 is also superior to the liquidcrystal display device A4 in terms of the lightness of white.

However, the aperture area ratio is 3:1 in the liquid crystal displaydevice B5 in Table 4, and it is 1.86:1 in the liquid crystal displaydevice D3 in Table 6. The ratio in each device is larger than that ofthe liquid crystal display device A4 in Table 3 in accordance withpreferred embodiment 1. As mentioned above, it is preferable that theliquid crystal display device A4 in Table 3 in accordance with preferredembodiment 1 is selected depending on the pixel design and the drivingcircuit device. That is, in some cases, preferred embodiment 1 is betterthan preferred embodiment 2.

Preferred Embodiment 3

As mentioned in preferred embodiment 2, the preferred embodiment inwhich the red sub-pixel has the largest aperture area and the green oryellow sub-pixel has the smallest aperture area is advantage in that thereduction in lightness of white can be minimized. In the presentpreferred embodiment, the following preferred embodiment is mentioned asa more preferable preferred embodiment: the aperture areas of the bluesub-pixel as well as the red sub-pixel are equivalently large and theaperture areas of the green and yellow sub-pixels are equivalentlysmall.

In the present preferred embodiments, six liquid crystal display devicesE1 to E6 shown in Table 7 were prepared. In each case, the apertureareas of the red and blue sub-pixels are equivalently large and theaperture areas of the green and yellow sub-pixels are equivalentlysmall. Table 7 shows an aperture area ratio among the respectivesub-pixels, an aperture area ratio between the sub-pixel having thelargest aperture area (red or blue sub-pixel) and the sub-pixel havingthe smallest aperture area (green or yellow sub-pixel), a lightness ofred, a lightness of white, an average transmittance of the colorfilters, and a light-emitting efficiency of the light source of thebacklight, in the liquid crystal display devices E1 to E6 prepared inthe present preferred embodiment.

TABLE 7 The largest Light- aperture area/ Color filter emitting Aperturearea ratio The smallest Lightness Lightness transmittance efficiency of(red:green:blue:yellow) aperture area of red (%) of white (%) backlightE1 11:9:11:9 1.22 12.1 102 38.1 0.85 E2 12:8:12:8 1.50 13.9 101 35.50.90 E3 13:7:13:7 1.86 15.3 100 32.7 0.97 E4 14:6:14:6 2.33 17.0 97 29.61.04 E5 15:5:15:5 3.00 18.7 92 26.2 1.11 E6 16:4:16:4 4.00 20.5 85 22.61.19

Each of FIGS. 17 and 18 shows a schematic view of the liquid crystaldisplay device in Table 7. FIG. 17 shows a configuration of a pixel 11 gdefining a display surface 500 g of the liquid crystal display device,and the pixel 11 g includes four sub-pixels 5Rg, 5Gg, 5Bg, and 5Ygarranged in a stripe pattern. FIG. 18 shows a configuration of a pixel11 h defining a display surface 500 h of the liquid crystal displaydevice, and the pixel 11 h includes four sub-pixels 5Rh, 5Gh, 5Bh, and5Yh arranged in two rows and two columns.

FIG. 19 shows a relationship between a lightness of red and a lightnessof white displayed by the respective liquid crystal displays E1 to E6shown in Table 7. In FIG. 19, □ corresponds to the liquid crystaldisplay devices E1 to E5 in Table 7. For comparison, ⋄ shows the liquidcrystal display devices D1 to D6 in which the reduction in lightness ofwhite is small in accordance with preferred embodiment 2.

According to the present preferred embodiment, the liquid crystaldisplay devices D1 to D6 in preferred embodiment 2 are furtheradvantageous in terms of lightness of white, and especially in theliquid crystal display devices E1 to E3 in Table 7, the lightness ofwhite is higher than that in the conventional four-primary-color liquidcrystal display device (FIG. 36) in which four sub-pixels have the sameaperture area. In order to maximize the chromaticity of white, a yellowcomponent of light from the backlight needs to be increased as the bluesub-pixel has a larger aperture area. Therefore, the light-emittingefficiency can be improved. If the lightness of red is 19% or more,specifically if the liquid crystal display device E6 in Table 7 in thepresent preferred embodiment is compared with the liquid crystal displaydevice D6 in Table 6 in preferred embodiment 2, the present preferredembodiment is disadvantageous in terms of display of white, in somecases.

The pixel configuration of the liquid crystal display device in thepresent preferred embodiment is not limited to the configurations shownin FIGS. 17 and 18. For example, as shown in FIG. 20, a pixel 11 idefining a display surface 500 i is divided into six sub-pixels and twored sub-pixels 5R and two blue pixels 5B may be arranged. In FIG. 20,with regard to an aperture area ratio among respective sub-pixels 5Ri,5Gi, 5Bi, and 5Yi, red:green:blue:yellow is 2:1:2:1. Thus, a pluralityof red sub-pixels and a plurality of blue sub-pixels are arranged, andthereby modification of the pixel design and the driving circuit designcan be minimized.

As shown in FIG. 21, a pixel 11 j defining a display surface 500 j isdivided into six sub-pixels, and two red sub-pixels and two bluesub-pixel having different color characteristics are arranged. FIG. 22shows spectral characteristics of a color filter in this case. In thiscase, light having a dominant wavelength of about 460 nm passes througha blue sub-pixel 5B₁j, and light having a dominant wavelength of about488 nm passes through and a blue sub-pixel 5B₂j. Also in the case shownin FIG. 21, a red sub-pixel 5Rj, a green sub-pixel 5Gj, the bluesub-pixels 5B₁j and 5B₂j, and a yellow sub-pixel 5Yj have equivalentaperture areas. With regard to an aperture area ratio among therespective sub-pixels, red:green:blue:yellow is 2:1:1:2. Thus, two bluesub-pixels having different color characteristics are arranged, andthereby the color reproduction range can be further extended.

As shown in FIG. 23, a pixel 11 k defining a display surface 500 k isdivided into six sub-pixels, and two red sub-pixels having differentcolor characteristics and two blue sub-pixels are arranged. FIG. 13shows spectral characteristics of a color filter in this case. In thiscase, light having a dominant wavelength of about 612 nm passes througha red sub-pixel 5R₁k, and light having a dominant wavelength of about607 nm passes through a red sub-pixel 5R₂k. Also in the case shown inFIG. 23, the aperture areas of the red sub-pixels 5R₁k and 5R₂k, a greensub-pixel 5Gk, a blue sub-pixel 5Bk, and a yellow sub-pixel 5Yk areequivalent. With regard to an aperture area ratio among the respectivesub-pixels, red:green:blue:yellow is 2:1:1:2. Thus, even by arrangingthe red sub-pixels having different color characteristics, the colorreproduction range can be further extended.

Further, as shown in FIG. 24, a pixel 11 m defining a display surfaceabout 500 m is divided into six sub-pixels, and two red sub-pixelshaving different color characteristics and two blue sub-pixels havingdifferent color characteristics are arranged. Each of FIGS. 13 and 22shows spectral characteristics of a color filter in this case. Also inthe case shown in FIG. 24, the aperture areas of red sub-pixels 5R₁m and5R₂m, a green sub-pixel 5Gm, blue sub-pixels 5B₁m and 5B₂m, and a yellowsub-pixel 5Ym are equivalent. With regard to an aperture area ratioamong the respective sub-pixels, red: green: blue: yellow is 2:1:1:2.Thus, even by arranging the red sub-pixels having different colorcharacteristics and the blue sub-pixels having different colorcharacteristics, the color reproduction range can be further extended.These pixel configurations are just mentioned as one example, and thepresent preferred embodiment is not limited to these pixelconfigurations.

Preferred Embodiment 4

According to preferred embodiment 3, the preferred embodiment in whichthe aperture areas of the red and blue sub-pixels are equivalently largeand the aperture areas of the green and yellow sub-pixels areequivalently small is mentioned. According to the present preferredembodiment, an preferred embodiment in which green and yellow sub-pixelswhich have small aperture areas are arranged to be different in aperturearea ratio.

Table 8 shows an aperture area ratio among the respective sub-pixels, anaperture area ratio between the sub-pixel having the largest aperturearea (red or blue sub-pixel) and the sub-pixel having the smallestaperture area (green sub-pixel), a lightness of red, a lightness ofwhite, an average transmittance of the color filters, and alight-emitting efficiency of the light source of the backlight, inliquid crystal display devices F1 to F4 prepared in the presentpreferred embodiment, in the case that aperture areas of the red andblue sub-pixel are equivalently large and an aperture area of the greensub-pixel is small.

TABLE 8 The largest Light- aperture area/ Color filter emitting Aperturearea ratio The smallest Lightness Lightness transmittance efficiency of(red:green:blue:yellow) aperture area of red (%) of white (%) backlightF1 11:8:11:10 1.38 11.8 103 38.6 0.84 F2 12:6:12:10 2.00 12.3 103 36.40.90 F3 13:4:13:10 3.25 13.0 103 33.9 0.96 F4 14:2:14:10 7.00 13.9 10131.2 1.03

Each of FIGS. 25 and 26 schematically shows a liquid crystal displaydevice in Table 8. FIG. 25 shows a configuration of a pixel 11 ndefining a display surface 500 n of the liquid crystal display device,and the pixel 11 n includes four sub-pixels 5Rn, 5Gn, 5Bn, and 5Ynarranged in a stripe pattern. FIG. 26 shows a configuration of a pixel11 p defining a display surface 500 p of the liquid crystal displaydevice, and the pixel 11 p includes four sub-pixels 5Rp, 5Gp, 5Bp, and5Yp arranged in two rows and two columns. These pixel configurations arejust mentioned as one example. The present preferred embodiment is notespecially limited to these pixel configurations.

Table 9 shows an aperture area ratio among the respective sub-pixels, anaperture area ratio between the sub-pixel having the largest aperturearea (red or blue sub-pixel) and the sub-pixel having the smallestaperture area (yellow sub-pixel), a lightness of red, a lightness ofwhite, an average transmittance of the color filters, and alight-emitting efficiency of the light source of the backlight, inliquid crystal display devices G1 to G3 prepared in the presentpreferred embodiment, in the case that aperture areas of the red andblue sub-pixel are equivalently large and an aperture area of the yellowsub-pixel is small.

TABLE 9 The largest Light- aperture area/ Color filter emitting Aperturearea ratio The smallest Lightness Lightness transmittance efficiency of(red:green:blue:yellow) aperture area of red (%) of white (%) backlightG1 11:10:11:8 1.38 13.0 100 37.5 0.84 G2 12:10:12:6 2.00 15.2 99 34.40.91 G3 13:10:13:4 3.25 18.0 96 31.1 0.98

FIG. 27 shows a relationship between a lightness of red and a lightnessof white displayed by the liquid crystal displays shown in Tables 8 and9. In FIG. 27, Δ corresponds to the liquid crystal display device inTable 8; and ∘ corresponds to the liquid crystal display device in Table9. For comparison, □ shows the liquid crystal display devices E1 to E6in Table 7 in accordance with the preferred embodiment 3 in which theaperture areas of the red and blue sub-pixels are equivalently large andthe aperture areas of the green and yellow sub-pixels are equivalentlysmall.

FIG. 27 shows that the liquid crystal display devices F1 to F4 in Table8 in the present preferred embodiment are superior in lightness of whiteto the liquid crystal display devices E1 to E4 in Table 7 in preferredembodiment 3, although the lightness of red is small in the liquidcrystal display devices F1 to F4. However, if two liquid crystal displaydevices that are the same in the aperture area ratio among thesub-pixels, i.e., the liquid crystal display device F3 in Table 8 andthe liquid crystal display device G3 in Table 9, are compared, thelightness of white is high, but a large effect of improving thelightness of red cannot be obtained and the lightness of red cannot beincreased to about 14% or more according to the liquid crystal displaydevice F3 in Table 8. In contrast, according to the liquid crystaldisplay device G3 in Table 9, the lightness of white is not so high, buta large effect of improving the lightness of red can be obtained. Alsoin this case, the preferred embodiment may be appropriately selecteddepending on a desired lightness of red. The liquid crystal displaydevices G1 to G3 in Table 9 in the present preferred embodiment aresuperior in lightness of red to the liquid crystal display devices E1 toE3 in Table 7 in preferred embodiment 3, although the lightness of whiteis small in the liquid crystal display devices G1 to G3.

Preferred Embodiment 5

As shown in preferred embodiments 1 and 4, if the aperture areas of bothof the red and blue sub-pixels are large, the average transmittance ofthe color filters is reduced in comparison to the case that only theaperture area of the red sub-pixel is large. However, the proportion ofthe blue component which passes through the color filter is increased.Therefore, with regard to the wavelength characteristics of thebacklight used, the blue component whose light-emitting efficiency islow can be decreased. Therefore, a light source having a highlight-emitting efficiency can be used as the backlight. As a result, ifthe average transmittance of the color filters and the light-emittingefficiency of the light source of the backlight are taken intoconsideration, the light-emitting efficiency of the light source of thebacklight can be high enough to compensate the reduction of the averagetransmittance of the color filter due to the increase in aperture areaof the blue sub-pixel. According to preferred embodiments 1 to 4, thecase where at least red sub-pixel has the largest aperture area ismentioned. In the present preferred embodiment, the case where the bluesub-pixel has the largest aperture area is mentioned.

Table 10 shows an aperture area ratio among the respective sub-pixels,an aperture area ratio between the sub-pixel having the largest aperturearea (blue sub-pixel) and the sub-pixel having the smallest aperturearea (green or yellow sub-pixel), a lightness of red, a lightness ofwhite, an average transmittance of the color filters, and alight-emitting efficiency of the light source of the backlight, inliquid crystal display devices H1 to H4 prepared in the presentPreferred embodiment, in the case that an aperture area of the bluesub-pixel is large and aperture areas of the green and yellow sub-pixelsare equivalently small.

TABLE 10 The largest Light- aperture area/ Color filter emittingAperture area ratio The smallest Lightness Lightness transmittanceefficiency of (red:green:blue:yellow) aperture area of red (%) of white(%) backlight H1 10:9:12:9 1.33 11.7 105 38.1 0.87 H2 10:8:14:8 1.7512.6 106 35.4 0.95 H3 10:7:16:7 2.29 13.5 104 32.4 1.02 H4 10:6:18:63.00 14.8 101 29.2 1.09

Each of FIGS. 28 and 29 schematically shows a liquid crystal displaydevice in Table 10. FIG. 28 shows a configuration of a pixel 11 qdefining a display surface 500 q of the liquid crystal display device,and the pixel 11 q includes four sub-pixels 5Rq, 5Gq, 5Bq, and 5Yqarranged in a stripe pattern. FIG. 29 shows a configuration of a pixel11 r defining a display surface 500 r of the liquid crystal displaydevice, and the pixel 11 r includes four sub-pixels 5Rr, 5Gn, 5Br, and5Yr arranged in two rows and two columns. These pixel configurations arejust mentioned as one example. The present preferred embodiment is notlimited to these pixel configurations.

Table 11 shows an aperture area ratio among the respective sub-pixels,an aperture area ratio between the sub-pixel having the largest aperturearea (blue sub-pixel) and the sub-pixel having the smallest aperturearea (green sub-pixel), a lightness of red, a lightness of white, anaverage transmittance of the color filters, and a light-emittingefficiency of the light source of the backlight, in liquid crystaldisplay devices I1 to I4 prepared in the present Preferred embodiment,in the case that an aperture area of the blue sub-pixel is large and anaperture area of the green sub-pixel is small.

TABLE 11 The largest Light- aperture area/ Color filter emittingAperture area ratio The smallest Lightness Lightness transmittanceefficiency of (red:green:blue:yellow) aperture area of red (%) of white(%) backlight I1 10:9:11:10 1.33 11.1 103 39.0 0.83 I2 10:8:12:10 1.7511.2 105 37.5 0.86 I3 10:7:13:10 2.29 11.3 107 35.9 0.90 I4 10:6:14:103.00 11.3 108 34.2 0.94

Table 12 shows an aperture area ratio among the respective sub-pixels,an aperture area ratio between the sub-pixel having the largest aperturearea (blue sub-pixel) and the sub-pixel having the smallest aperturearea (yellow sub-pixel), a lightness of red, a lightness of white, anaverage transmittance of the color filters, and a light-emittingefficiency of the light source of the backlight, in liquid crystaldisplay devices J1 to J4 prepared in the present preferred embodiment,in the case that an aperture area of the blue sub-pixel is large and anaperture area of the yellow sub-pixel is small.

TABLE 12 The largest Light- aperture area/ Color filter emittingAperture area ratio The smallest Lightness Lightness transmittanceefficiency of (red:green:blue:yellow) aperture area of red (%) of white(%) backlight J1 10:10:11:9 1.33 11.7 102 39.0 0.83 J2 10:10:12:8 1.7512.5 103 37.5 0.87 J3 10:10:13:7 2.29 13.2 103 35.9 0.91 J4 10:10:14:63.00 14.2 102 34.2 0.95

FIG. 30 shows a relationship between a lightness of red and a lightnessof white displayed by the liquid crystal displays shown in Tables 10 to12. In FIG. 30, ⋄ corresponds to the liquid crystal display device inTable 10; □ corresponds to the liquid crystal display device in Table11; and Δ corresponds to the liquid crystal display device in Table 12.For comparison, ∘ shows the liquid crystal display devices E1 to E6 inTable 7 in accordance with the preferred embodiment 3 in which theaperture areas of the red and blue sub-pixels are equivalently large andthe aperture areas of the green and yellow sub-pixels are equivalentlysmall.

According to the liquid crystal display devices I1 to I4 in Table 11,the effect of improving the lightness of white can be observed, but theeffect of improving the lightness of red is hardly observed. Incontrast, the lightness of white is about 106% when the lightness of redis about 12.6% in the liquid crystal display device H2 in Table 10; thelightness of white is about 103% when the lightness of red is about12.5% in the liquid crystal display device J2 in Table 12. Thus, theliquid crystal display devices H2 and J2 are excellent in lightness ofwhite. However, according to the present preferred embodiment, thelightness of red is not so increased. Therefore, if the lightness of redneeds to be increased to about 15% or more, it is preferable that anappropriate liquid crystal display device is selected from those inpreferred embodiments 1 to 4.

The pixel configuration of the liquid crystal display device in thepresent preferred embodiment is not limited to those shown in FIGS. 28and 29. For example, as shown in FIG. 31, a pixel 11 s defining adisplay surface 500 s is divided into five sub-pixels and two bluesub-pixels 5B may be arranged. In FIG. 31, with regard to an aperturearea ratio among the respective sub-pixels 5Rs, 5Gs, 5Bs, and 5Ys,red:green:blue:yellow is 1:1:2:1. Thus, a plurality of blue sub-pixelsare arranged, and thereby modification of the pixel design and thedriving circuit design can be minimized.

As shown in FIG. 32, a pixel 11 t defining a display surface 500 t isdivided into five pixels, and two blue sub-pixels having different colorcharacteristics may be arranged. FIG. 22 shows spectral characteristicsof a color filter in this case. In this case, light having a dominantwavelength of about 460 nm passes through a blue sub-pixel 5B₁t, andlight having a dominant wavelength of about 488 nm passes through a bluesub-pixel 5B₂t. Also in the case shown in FIG. 32, aperture areas of ared sub-pixel 5Rt, a green sub-pixel 5Gt, the blue sub-pixels 5B₁t and5B₂t, and a yellow sub-pixel 5Yt are equivalent. With regard to anaperture area ratio among the respective sub-pixels,red:green:blue:yellow is 2:1:1:2. Thus, two blue sub-pixels havingdifferent color characteristics are arranged, and thereby the colorreproduction range can be further extended. These pixel configurationsare just mentioned as one example. The present preferred embodiment isnot limited to these pixel configurations.

Preferred Embodiment 6

The present preferred embodiment shows a case where the yellow sub-pixelhas the smallest aperture area.

Table 13 shows an aperture area ratio among the respective sub-pixels,an aperture area ratio between the sub-pixel having the largest aperturearea (red, green, or blue sub-pixel) and the sub-pixel having thesmallest aperture area (yellow sub-pixel), a lightness of red, alightness of white, an average transmittance of the color filters, and alight-emitting efficiency of the light source of the backlight, inliquid crystal display devices K1 to K5 prepared in the presentpreferred embodiment, in the case that an aperture area of the yellowsub-pixel is small and aperture areas of the other sub-pixels areequivalently large.

TABLE 13 The largest Light- aperture area/ Color filter emittingAperture area ratio The smallest Lightness Lightness transmittanceefficiency of (red:green:blue:yellow) aperture area of red (%) of white(%) backlight K1 10.5:10.5:10.5:8.5 1.24 12.2 100.0 38.7 1.00 K211:11:11:7 1.57 13.6 99.0 37.0 0.99 K3 11.5:11.5:11.5:5.5 2.09 15.2 98.235.2 0.98 K4 12:12:12:4 3.00 17.3 95.6 33.3 0.96 K5 12.5:12.5:12.5:2.55.00 19.3 93.5 31.3 0.94

Each of FIGS. 33 and 34 schematically shows a liquid crystal displaydevice in Table 13. FIG. 33 shows a configuration of a pixel 11 udefining a display surface 500 u of the liquid crystal display, and thepixel 11 u includes four sub-pixels 5Ru, 5Gu, 5Bu, and 5Yu arranged in astripe pattern. FIG. 34 shows a configuration of a pixel 11 v defining adisplay surface 500 v of the liquid crystal display, and the pixel 11 vincludes four sub-pixels 5Rv, 5Gv, 5Bv, and 5Yv arranged in two rows andtwo columns. These pixel configurations are just mentioned as oneexample. The present preferred embodiment is not limited to these pixelconfigurations.

Table 14 shows an aperture area ratio among the respective sub-pixels,an aperture area ratio between the sub-pixel having the largest aperturearea (red or green sub-pixel) and the sub-pixel having the smallestaperture area (yellow sub-pixel), a lightness of red, a lightness ofwhite, an average transmittance of the color filters, and alight-emitting efficiency of the light source of the backlight, inliquid crystal display devices L1 to L4 prepared in the presentpreferred embodiment, in the case that an aperture area of the yellowsub-pixel is small and aperture areas of the red and green sub-pixelsare equivalently large.

TABLE 14 The largest Light- aperture area/ Color filter emittingAperture area ratio The smallest Lightness Lightness transmittanceefficiency of (red:green:blue:yellow) aperture area of red (%) of white(%) backlight L1 11:11:10:8 1.24 13.0 100.6 37.6 0.85 L2 12:12:10:6 1.5715.2 98.6 34.4 0.91 L3 13:13:10:4 3.25 18.0 95.9 31.1 0.98 L4 14:14:14:27.00 21.3 90.8 27.5 1.04

FIG. 35 shows a relationship between a lightness of red and a lightnessof white displayed by the liquid crystal displays shown in Tables 13 and14. In FIG. 35, Δ corresponds to the liquid crystal display devices K1to K5 in Table 13; and ⋄ corresponds to the liquid crystal displaydevice in Table 14. For comparison, ∘ shows the liquid crystal displaydevices E1 to E6 in Table 7 in accordance with the preferred embodiment3 in which the aperture areas of the red and blue sub-pixels areequivalently large and the aperture areas of the green and yellowsub-pixels are equivalently small.

According to the liquid crystal display devices in Tables 13 and 14, theaperture area ratio needs to be increased, but the light-emittingefficiency of the light source of the backlight is increased. Therefore,such liquid crystal display devices are advantageously employed in orderto increase the lightness of red.

Preferred Embodiment 7

The present preferred embodiment shows a case where red, blue, green,and yellow sub-pixels are ranked in descending order of aperture area.

Table 15 shows an aperture area ratio among the respective sub-pixels,an aperture area ratio between the sub-pixel having the largest aperturearea (red sub-pixel) and the sub-pixel having the smallest aperture area(yellow sub-pixel), a lightness of red, a lightness of white, an averagetransmittance of the color filters, and a light-emitting efficiency ofthe light source of the backlight, in liquid crystal display devices M1and M2 prepared in the present preferred embodiment.

TABLE 15 The largest Light- aperture area/ Color filter emittingAperture area ratio The smallest Lightness Lightness transmittanceefficiency of (red:green:blue:yellow) aperture area of red (%) of white(%) backlight M1 10:8:9:7 1.42 13.2 92.5 37.4 0.84 M2 10:6:8:4 2.50 17.288.7 32.5 0.93

According to the liquid crystal display device in Table 15, the aperturearea of the red sub-pixel is relatively large and therefore the effectof improving the lightness of red is large. In addition, the bluesub-pixel has a relatively large aperture area, and the yellow sub-pixelhas a small aperture area. Therefore, a light source having a highlight-emitting efficiency can be used in order to maximize thechromaticity of white. Therefore, the lightness of red is increased at arelatively small aperture area ratio. As a result, the reduction in thelightness of white can be minimized.

Preferred Embodiment 8

The present preferred embodiment shows a case where red, blue, yellow,and green sub-pixels are ranked in descending order of aperture area.

Table 16 shows an aperture area ratio among the respective sub-pixels,an aperture area ratio between the sub-pixel having the largest aperturearea (red sub-pixel) and the sub-pixel having the smallest aperture area(green sub-pixel), a lightness of red, a lightness of white, an averagetransmittance of the color filters, and a light-emitting efficiency ofthe light source of the backlight, in liquid crystal display devices N1to N3 prepared in the present preferred embodiment.

TABLE 16 The largest Light- aperture area/ Color filter emittingAperture area ratio The smallest Lightness Lightness transmittanceefficiency of (red:green:blue:yellow) aperture area of red (%) of white(%) backlight N1 12:9:11:10 1.33 12.2 100.3 38.3 0.83 N2 14:8:12:10 1.7513.2 99.6 36.3 0.87 N3 16:8:14:10 2.00 14.1 99.5 34.4 0.92

According to the liquid crystal display devices in Table 16, the redsub-pixel has the largest aperture area, and therefore the effect ofimproving the lightness of red is large. In addition, the blue sub-pixelhas a relatively large aperture area and the yellow sub-pixel has arelatively small aperture area. Therefore, a light source having a highlight-emitting efficiency can be used in order to maximize thechromaticity of white. Therefore, the lightness of red can be improvedat a relatively small aperture area ratio. As a result, the reduction inlightness of white can be minimized.

Preferred Embodiment 9

The present preferred embodiment shows a case where red, green, blue,and yellow sub-pixels are ranked in descending order of aperture area.

Table 17 shows an aperture area ratio among the respective sub-pixels,an aperture area ratio between the sub-pixel having the largest aperturearea (red sub-pixel) and the sub-pixel having the smallest aperture area(yellow sub-pixel), a lightness of red, a lightness of white, an averagetransmittance of the color filters, and a light-emitting efficiency ofthe light source of the backlight, in liquid crystal display devices O1to O6 prepared in the present preferred embodiment.

TABLE 17 The largest Light- aperture area/ Color filter emittingAperture area ratio The smallest Lightness Lightness transmittanceefficiency of (red:green:blue:yellow) aperture area of red (%) of white(%) backlight O1 12:11:10:9 1.33 13.0 96.3 38.7 0.79 O2 12:11:10:8 1.5013.7 96.0 37.9 0.80 O3 14:12:10:8 1.75 14.5 92.5 37.2 0.79 O4 16:14:10:82.00 15.4 89.0 36.9 0.76 O5 14:13:12:7 2.00 15.2 95.9 35.9 0.84 O614:13:12:6 2.33 15.8 95.4 35.0 0.86

According to the liquid crystal display devices in Table 17, the redsub-pixel has a large aperture area, and therefore the effect ofimproving the lightness of red is large. In addition, the yellowsub-pixel has a small aperture area. Therefore, a light source with ahigh light-emitting efficiency can be used in order to maximize thechromaticity of white. Therefore, the lightness of red can be improvedat a relatively small aperture area ratio. As a result, the reduction inlightness of white can be minimized.

Preferred Embodiment 10

The present preferred embodiment shows a case where red, blue, yellow,and green sub-pixels are ranked in descending order of aperture area.

Table 18 shows an aperture area ratio among the respective sub-pixels,an aperture area ratio between the sub-pixel having the largest aperturearea (red sub-pixel) and the sub-pixel having the smallest aperture area(yellow or green sub-pixel), a lightness of red, a lightness of white,an average transmittance of the color filters, and a light-emittingefficiency of the light source of the backlight, in liquid crystaldisplay devices P1 to P3 prepared in the present preferred embodiment.

TABLE 18 The largest Light- aperture area/ Color filter emittingAperture area ratio The smallest Lightness Lightness transmittanceefficiency of (red:green:blue:yellow) aperture area of red (%) of white(%) backlight P1 12:9:10:9 1.33 12.9 97.8 38.0 0.82 P2 14:8:10:8 1.7514.8 94.5 35.3 0.85 P3 16:7:10:7 2.29 16.7 91.2 32.4 0.89

According to the liquid crystal display devices in Table 18, the redsub-pixel has a large aperture area, and therefore the effect ofimproving the lightness of red is large. In addition, the aperture areaof the blue sub-pixel is relatively large and the aperture areas of theyellow and green sub-pixels are small. Therefore, a light source with ahigh light-emitting efficiency can be used in order to maximize thechromaticity of white. Therefore, the lightness of red can be improvedat a relatively small aperture area. As a result, the reduction inlightness of white can be minimized.

Preferred Embodiment 11

The present preferred embodiment shows a case where blue, red, green,and yellow sub-pixels are ranked in descending order of aperture area.

Table 19 shows an aperture area ratio among the respective sub-pixels,an aperture area ratio between the sub-pixel having the largest aperturearea (blue sub-pixel) and the sub-pixel having the smallest aperturearea (red sub-pixel), a lightness of red, a lightness of white, anaverage transmittance of the color filters, and a light-emittingefficiency of the light source of the backlight, in liquid crystaldisplay devices Q1 and Q2 prepared in the present preferred embodiment.

TABLE 19 The largest Light- aperture area/ Color filter emittingAperture area ratio The smallest Lightness Lightness transmittanceefficiency of (red:green:blue:yellow) aperture area of red (%) of white(%) backlight Q1 9:8:10:7 1.42 12.6 95.9 37.5 0.87 Q2 8:6:10:4 2.50 15.294.1 32.3 0.99

According to the liquid crystal display devices in Table 19, the redsub-pixel has a relatively large aperture area and therefore the effectof improving the lightness of red is large. In addition, the aperturearea of the blue sub-pixel is large and the aperture area of the yellowsub-pixel is small. Therefore, a light source having a highlight-emitting efficiency can be used in order to maximize thechromaticity of white. Therefore, the lightness of red can be improvedat a relatively small aperture area ratio. As a result, the reduction inlightness of white can be minimized.

Preferred Embodiment 12

The present embodiment shows a case where blue, red, yellow, and greensub-pixels are ranked in descending order of aperture area.

Table 20 shows an aperture area ratio among the respective sub-pixels,an aperture area ratio between the sub-pixel having the largest aperturearea (red sub-pixel) and the sub-pixel having the smallest aperture area(green sub-pixel), a lightness of red, a lightness of white, an averagetransmittance of the color filters, and a light-emitting efficiency ofthe light source of the backlight, in liquid crystal display devices R1to R3 prepared in the present preferred embodiment.

TABLE 20 The largest Light- aperture area/ Color filter emittingAperture area ratio The smallest Lightness Lightness transmittanceefficiency of (red:green:blue:yellow) aperture area of red (%) of white(%) backlight R1 11:9:12:10 1.33 11.6 103.9 38.4 0.85 R2 12:8:14:10 1.7512.2 105.1 36.4 0.91 R3 15:8:16:10 2.00 13.7 102.6 34.0 0.95

According to the liquid crystal display devices in Table 20, theaperture area of the red sub-pixel is relatively large and therefore theeffect of improving the lightness of red is large. Further, the aperturearea of the blue sub-pixel is large and the aperture areas of the yellowsub-pixel are relatively small. Therefore, a light source with a highlight-emitting efficiency can be used in order to maximize thechromaticity of white. Therefore, the lightness of red can be improvedat a relatively small aperture area ratio. As a result, the reduction inlightness of white can be minimized.

Preferred Embodiment 13

The present preferred embodiment shows a case where blue, green, red,and yellow sub-pixels are ranked in descending order of aperture area.

Table 21 shows an aperture area ratio among the respective sub-pixels,an aperture area ratio between the sub-pixel having the largest aperturearea (red sub-pixel) and the sub-pixel having the smallest aperture area(yellow sub-pixel), a lightness of red, a lightness of white, an averagetransmittance of the color filters, and a light-emitting efficiency ofthe light source of the backlight, in liquid crystal display devices S1to S7 prepared in the present preferred embodiment.

TABLE 21 The largest Light- aperture area/ Color filter emittingAperture area ratio The smallest Lightness Lightness transmittanceefficiency of (red:green:blue:yellow) aperture area of red (%) of white(%) backlight S1 10:11:12:8 1.50 12.3 102.5 37.9 0.86 S2 10:11:12:7 1.7113.0 102.3 36.9 0.88 S3 10:11:12:7 1.71 13.3 101.9 36.9 0.87 S410:11:12:6 2.00 13.9 101.0 35.8 0.89 S5 10:11:12:5 2.40 15.0 99.8 34.70.91 S6 11:12:13:6 2.17 14.6 99.8 35.3 0.89 S7 13:14:15:6 2.50 15.5 98.934.4 0.91

According to the liquid crystal display devices in Table 21, theaperture area of the yellow sub-pixel is particularly small. Therefore,a red component of light can be emitted at a high intensity from abacklight, and therefore, the effect of improving the lightness of redis large. In addition, the aperture area of the blue sub-pixel is largeand the aperture area of the yellow sub-pixel is small. Therefore, alight source with a high light-emitting efficiency can be used in orderto maximize the chromaticity of white. Therefore, the lightness of redcan be improved at a relatively small aperture area ratio. As a result,the reduction in lightness of white can be minimized.

Preferred Embodiment 14

The present preferred embodiment shows a case where blue and greensub-pixels, followed by red and yellow sub-pixels, are ranked indescending order of aperture area.

Table 22 shows an aperture area ratio among the respective sub-pixels,an aperture area ratio between the sub-pixel having the largest aperturearea (blue or green sub-pixel) and the sub-pixel having the smallestaperture area (yellow sub-pixel), a lightness of red, a lightness ofwhite, an average transmittance of the color filters, and alight-emitting efficiency of the light source of the backlight, inliquid crystal display devices T1 to T3 prepared in the presentpreferred embodiment.

TABLE 22 The largest Light- aperture area/ Color filter emittingAperture area ratio The smallest Lightness Lightness transmittanceefficiency of (red:green:blue:yellow) aperture area of red (%) of white(%) backlight T1 9:10:10:7 1.43 12.5 100.8 38.2 0.83 T2 9:10:10:5 2.0014.4 99.9 35.9 0.88 T3 9:10:10:4 2.50 15.7 98.2 34.6 0.90

According to the liquid crystal display in Table 22, the aperture areaof the yellow sub-pixel is particularly small. Therefore, a redcomponent of light can be emitted at a higher intensity from a backlightand the like. Therefore, the effect of improving the lightness of red islarge. In addition, the aperture area of the blue sub-pixel is large andthe aperture area of the yellow sub-pixel is small. Therefore, alightsource with a high light-emitting efficiency can be used in order tomaximize the chromaticity of white. Therefore, the lightness of red canbe improved at a relatively small aperture area ratio. As a result, thereduction in lightness of white can be minimized.

As mentioned above, preferred embodiments 1 to 14 show the case wherethe color filter having spectral characteristics in FIG. 7, 13, or 22 isused. However, the color filter is not limited thereto, and even using acolor filter different in hue or chroma from that of these preferredembodiments, the effect of improving the lightness of red can beobserved. Specifically, such a color filter can be applied to a displaydevice in which light having a dominant wavelength of about 595 nm ormore and about 650 nm or less passes through a red sub-pixel; lighthaving a dominant wavelength of about 490 nm or more and about 555 nm orless passes through a green sub-pixel; light having a dominantwavelength of about 450 nm or more and about 490 nm or less passesthrough a blue sub-pixel; light having a dominant wavelength of about565 nm or more and about 580 nm or less passes through a yellowsub-pixel. Preferred embodiments 1 to 14 show the configuration in whichthe pixel is defined by the red, green, blue, and yellow sub-pixels. Thepixel configuration is not limited thereto. The same effect can beobtained even in the case where the pixel is defined by red, green,blue, yellow, and magenta sub-pixels.

According to preferred embodiments 1 to 14, a common CCFT is used as thelight source of the backlight, but the light source is not limitedthereto. The above-mentioned effect of improving the lightness of redcan be observed even using a backlight different from that used inpreferred embodiments, such as a white light-emitting diode (acombination of a blue LED and a yellow fluorescence), RGB-LED, a hotcathode fluorescent tube (HCFT), an organic electroluminescence, and afield emission display (FED).

In addition, according to preferred embodiments 1 to 14, the mixingratio among the fluorescent materials of red, green, and blue, is variedto adjust spectral characteristics of the light source, and thereby thechromaticity of white displayed by the liquid crystal display device ismaximized. However, the way of optimizing the chromaticity of white isnot limited thereto. For example, the chromaticity of white displayed bythe liquid crystal display device may be maximized by modifying anoptical design of a liquid crystal layer or an optical film, or varyingan applied voltage at the time of display of white.

According to preferred embodiments 1 to 14, a transmissive liquidcrystal display device which performs display using a backlight is used.However, in addition to the transmissive liquid crystal display device,the present invention can be preferably used in liquid crystal displaydevices in other display systems such as a transflective liquid crystaldisplay device which performs transmissive display using a backlight andperforms reflective display using external light and/or a front lightand a reflective liquid crystal display device which performs displayusing a light source such as a front light, or used in various displaydevices such as a cathode ray tube (CRT), an organic electroluminescentdisplay device (OELD), a plasma display panel (PDP), and a fieldemission displays (FED) such as a surface-conduction electron-emitterdisplay (SED).

In the present description, if the terms “or more” and “or less” areused, the value (boundary value) is included.

The present application claims priority under the Paris Convention andthe domestic law in the country to be entered into national phase onPatent Application No. 2006-169206 filed in Japan on Jun. 19, 2006, theentire contents of which are hereby incorporated by reference.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing the scope andspirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

The invention claimed is:
 1. A display device comprising a displaysurface, the display surface including a pixel consisting of red, green,blue, and yellow sub-pixels, wherein the display device includes red,green, blue, and yellow color filters, and a light source device, thered sub-pixel has the largest aperture area, and the blue sub-pixel hasthe largest aperture area, the aperture area of the red sub-pixel islarger than that of the green sub-pixel and also larger than that of theyellow sub-pixel, the aperture area of the blue sub-pixel is larger thanthat of the green sub-pixel and also larger than that of the yellowsub-pixel, and a lightness of red accounts for 12% or more and 25% orless relative to a lightness of white.
 2. The display device accordingto claim 1, wherein the green sub-pixel has the smallest aperture area,and the yellow sub-pixel has the smallest aperture area.
 3. The displaydevice according to claim 2, wherein the aperture areas of the redsub-pixel is 1.22 to 1.86 times as large as that of each of the greenand yellow sub-pixels, and the aperture area of the blue sub-pixel is1.22 to 1.86 times as large as that of each of the green and yellowsub-pixels.
 4. The display device according to claim 3, wherein in thepixel, the red sub-pixel is the largest in number, and the bluesub-pixel is the largest in number.
 5. The display device according toclaim 4, wherein the pixel includes blue sub-pixels different in colorcharacteristics.
 6. The display device according to claim 4, wherein thepixel includes red sub-pixels different in color characteristics.
 7. Thedisplay device according to claim 2, wherein the aperture area of thered sub-pixel is three times or less as large as an aperture area of asub-pixel whose aperture area is the smallest.
 8. The display deviceaccording to claim 7, wherein in the pixel, the red sub-pixel is thelargest in number, and the blue sub-pixel is the largest in number. 9.The display device according to claim 8, wherein the pixel includes bluesub-pixels different in color characteristics.
 10. The display deviceaccording to claim 8, wherein the pixel includes red sub-pixelsdifferent in color characteristics.
 11. The display device according toclaims 2, wherein in the pixel, the red sub-pixel is the largest innumber, and the blue sub-pixel is the largest in number.
 12. The displaydevice according to claim 11, wherein the pixel includes blue sub-pixelsdifferent in color characteristics.
 13. The display device according toclaim 11, wherein the pixel includes red sub-pixels different in colorcharacteristics.
 14. The display device according to claim 1, whereinthe aperture area of the red sub-pixel is three times or less as largeas an aperture area of a sub-pixel whose aperture area is the smallest.15. The display device according to claim 14, wherein in the pixel, thered sub-pixel is the largest in number, and the blue sub-pixel is thelargest in number.
 16. The display device according to claim 15, whereinthe pixel includes blue sub-pixels different in color characteristics.17. The display device according to claim 16, wherein the aperture areaof the green sub-pixel is smaller than the aperture area of the yellowsub-pixel, and the green sub-pixel has the smallest aperture area. 18.The display device according to claim 16, wherein the aperture area ofthe yellow sub-pixel is smaller than the aperture area of the greensub-pixel, and the yellow sub-pixel has the smallest aperture area. 19.The display device according to claim 15, wherein the pixel includes redsub-pixels different in color characteristics.
 20. The display deviceaccording to claim 19, wherein the aperture area of the green sub-pixelis smaller than the aperture area of the yellow sub-pixel, and the greensub-pixel has the smallest aperture area.
 21. The display deviceaccording to claim 19, wherein the aperture area of the yellow sub-pixelis smaller than the aperture area of the green sub-pixel, and the yellowsub-pixel has the smallest aperture area.
 22. The display deviceaccording to claim 15, wherein the aperture area of the green sub-pixelis smaller than the aperture area of the yellow sub-pixel, and the greensub-pixel has the smallest aperture area.
 23. The display deviceaccording to claim 15, wherein the aperture area of the yellow sub-pixelis smaller than the aperture area of the green sub-pixel, and the yellowsub-pixel has the smallest aperture area.
 24. The display deviceaccording to claim 14, wherein the aperture area of the green sub-pixelis smaller than the aperture area of the yellow sub-pixel, and the greensub-pixel has the smallest aperture area.
 25. The display deviceaccording to claim 14, wherein the aperture area of the yellow sub-pixelis smaller than the aperture area of the green sub-pixel, and the yellowsub-pixel has the smallest aperture area.
 26. The display deviceaccording to claim 1, wherein in the pixel, the red sub-pixel is thelargest in number, and the blue sub-pixel is the largest in number. 27.The display device according to claim 26, wherein the pixel includesblue sub-pixels different in color characteristics.
 28. The displaydevice according to claim 27, wherein the aperture area of the greensub-pixel is smaller than the aperture area of the yellow sub-pixel, andthe green sub-pixel has the smallest aperture area.
 29. The displaydevice according to claim 27, wherein the aperture area of the yellowsub-pixel is smaller than the aperture area of the green sub-pixel, andthe yellow sub-pixel has the smallest aperture area.
 30. The displaydevice according to claim 26, wherein the pixel includes red sub-pixelsdifferent in color characteristics.
 31. The display device according toclaim 30, wherein the aperture area of the green sub-pixel is smallerthan the aperture area of the yellow sub-pixel, and the green sub-pixelhas the smallest aperture area.
 32. The display device according toclaim 30, wherein the aperture area of the yellow sub-pixel is smallerthan the aperture area of the green sub-pixel, and the yellow sub-pixelhas the smallest aperture area.
 33. The display device according toclaim 26, wherein the aperture area of the green sub-pixel is smallerthan the aperture area of the yellow sub-pixel, and the green sub-pixelhas the smallest aperture area.
 34. The display device according toclaim 26, wherein the aperture area of the yellow sub-pixel is smallerthan the aperture area of the green sub-pixel, and the yellow sub-pixelhas the smallest aperture area.
 35. The display device according toclaim 1, wherein the aperture area of the green sub-pixel is smallerthan the aperture area of the yellow sub-pixel, and the green sub-pixelhas the smallest aperture area.
 36. The display device according toclaim 1, wherein the aperture area of the yellow sub-pixel is smallerthan the aperture area of the green sub-pixel, and the yellow sub-pixelhas the smallest aperture area.